diff --git a/.gitignore b/.gitignore
index 1824e34..3b9971a 100644
--- a/.gitignore
+++ b/.gitignore
@@ -57,6 +57,9 @@ docs/_build/
 # PyBuilder
 target/
 
-#pycharm stuff
+# Vim
+*.swp
+#
+# PyCharm
 .idea/
 
diff --git a/setup.py b/setup.py
index 22ee0ac..0fbad77 100644
--- a/setup.py
+++ b/setup.py
@@ -1,8 +1,10 @@
 #!/usr/bin/env python
-from setuptools import setup, find_packages
+from setuptools import find_packages, setup
 
 install_requires = [
     'pytz',
+    'six',
+    'python-dateutil',
 ]
 
 setup(
diff --git a/stix2/__init__.py b/stix2/__init__.py
index cef4356..187d18a 100644
--- a/stix2/__init__.py
+++ b/stix2/__init__.py
@@ -3,11 +3,49 @@
 # flake8: noqa
 
 from .bundle import Bundle
-from .common import ExternalReference, KillChainPhase
+from .other import ExternalReference, KillChainPhase, MarkingDefinition, \
+    GranularMarking, StatementMarking, TLPMarking
 from .sdo import AttackPattern, Campaign, CourseOfAction, Identity, Indicator, \
     IntrusionSet, Malware, ObservedData, Report, ThreatActor, Tool, \
     Vulnerability
 from .sro import Relationship, Sighting
-from .markings import MarkingDefinition, GranularMarking, StatementMarking, TLPMarking
-
+from .utils import get_dict
 from . import exceptions
+
+
+OBJ_MAP = {
+    'attack-pattern': AttackPattern,
+    'campaign': Campaign,
+    'course-of-action': CourseOfAction,
+    'identity': Identity,
+    'indicator': Indicator,
+    'intrusion-set': IntrusionSet,
+    'malware': Malware,
+    'marking-definition': MarkingDefinition,
+    'observed-data': ObservedData,
+    'report': Report,
+    'relationship': Relationship,
+    'threat-actor': ThreatActor,
+    'tool': Tool,
+    'sighting': Sighting,
+    'vulnerability': Vulnerability,
+}
+
+
+def parse(data):
+    """Deserialize a string or file-like object into a STIX object"""
+
+    obj = get_dict(data)
+
+    if 'type' not in obj:
+        # TODO parse external references, kill chain phases, and granular markings
+        pass
+    else:
+        try:
+            obj_class = OBJ_MAP[obj['type']]
+            return obj_class(**obj)
+        except KeyError:
+            # TODO handle custom objects
+            raise ValueError("Can't parse unknown object type!")
+
+    return obj
diff --git a/stix2/base.py b/stix2/base.py
index 130d8d3..05bf545 100644
--- a/stix2/base.py
+++ b/stix2/base.py
@@ -41,7 +41,7 @@ class _STIXBase(collections.Mapping):
 
         if prop_name in kwargs:
             try:
-                kwargs[prop_name] = prop.validate(kwargs[prop_name])
+                kwargs[prop_name] = prop.clean(kwargs[prop_name])
             except ValueError as exc:
                 raise InvalidValueError(self.__class__, prop_name, reason=str(exc))
 
@@ -56,6 +56,7 @@ class _STIXBase(collections.Mapping):
         if extra_kwargs:
             raise ExtraFieldsError(cls, extra_kwargs)
 
+        # Detect any missing required fields
         required_fields = get_required_properties(cls._properties)
         missing_kwargs = set(required_fields) - set(kwargs)
         if missing_kwargs:
diff --git a/stix2/bundle.py b/stix2/bundle.py
index 5785d43..85be3e1 100644
--- a/stix2/bundle.py
+++ b/stix2/bundle.py
@@ -1,7 +1,7 @@
 """STIX 2 Bundle object"""
 
 from .base import _STIXBase
-from .properties import IDProperty, TypeProperty, Property
+from .properties import IDProperty, Property, TypeProperty
 
 
 class Bundle(_STIXBase):
diff --git a/stix2/common.py b/stix2/common.py
index 6ad7052..29cbf62 100644
--- a/stix2/common.py
+++ b/stix2/common.py
@@ -1,32 +1,17 @@
 """STIX 2 Common Data Types and Properties"""
 
-from .base import _STIXBase
-from .properties import Property, BooleanProperty, ReferenceProperty, ListProperty
+from .other import ExternalReference, GranularMarking
+from .properties import (BooleanProperty, ListProperty, ReferenceProperty,
+                         TimestampProperty)
 from .utils import NOW
 
 COMMON_PROPERTIES = {
     # 'type' and 'id' should be defined on each individual type
-    'created': Property(default=lambda: NOW),
-    'modified': Property(default=lambda: NOW),
-    'external_references': Property(),
+    'created': TimestampProperty(default=lambda: NOW),
+    'modified': TimestampProperty(default=lambda: NOW),
+    'external_references': ListProperty(ExternalReference),
     'revoked': BooleanProperty(),
     'created_by_ref': ReferenceProperty(type="identity"),
-    'object_marking_refs': ListProperty(ReferenceProperty, element_type="marking-definition"),
-    'granular_markings': ListProperty(Property)
+    'object_marking_refs': ListProperty(ReferenceProperty(type="marking-definition")),
+    'granular_markings': ListProperty(GranularMarking),
 }
-
-
-class ExternalReference(_STIXBase):
-    _properties = {
-        'source_name': Property(required=True),
-        'description': Property(),
-        'url': Property(),
-        'external_id': Property(),
-    }
-
-
-class KillChainPhase(_STIXBase):
-    _properties = {
-        'kill_chain_name': Property(required=True),
-        'phase_name': Property(required=True),
-    }
diff --git a/stix2/markings.py b/stix2/markings.py
deleted file mode 100644
index aea0caa..0000000
--- a/stix2/markings.py
+++ /dev/null
@@ -1,76 +0,0 @@
-"""STIX 2.0 Marking Objects"""
-
-from .base import _STIXBase
-from .properties import IDProperty, TypeProperty, ListProperty, ReferenceProperty, Property, SelectorProperty
-from .utils import NOW
-
-
-class MarkingDefinition(_STIXBase):
-    _type = 'marking-definition'
-    _properties = {
-        'created': Property(default=lambda: NOW),
-        'external_references': Property(),
-        'created_by_ref': ReferenceProperty(type="identity"),
-        'object_marking_refs': ListProperty(ReferenceProperty, element_type="marking-definition"),
-        'granular_marking': ListProperty(Property, element_type="granular-marking"),
-        'type': TypeProperty(_type),
-        'id': IDProperty(_type),
-        'definition_type': Property(),
-        'definition': Property(),
-    }
-
-
-class GranularMarking(_STIXBase):
-    _properties = {
-        'marking_ref': ReferenceProperty(required=True, type="marking-definition"),
-        'selectors': ListProperty(SelectorProperty, required=True),
-    }
-
-
-class TLPMarking(_STIXBase):
-    # TODO: don't allow the creation of any other TLPMarkings than the ones below
-    _properties = {
-        'tlp': Property(required=True)
-    }
-
-
-class StatementMarking(_STIXBase):
-    _properties = {
-        'statement': Property(required=True)
-    }
-
-    def __init__(self, statement=None, **kwargs):
-        # Allow statement as positional args.
-        if statement and not kwargs.get('statement'):
-            kwargs['statement'] = statement
-
-        super(StatementMarking, self).__init__(**kwargs)
-
-
-TLP_WHITE = MarkingDefinition(
-                id="marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9",
-                created="2017-01-20T00:00:00.000Z",
-                definition_type="tlp",
-                definition=TLPMarking(tlp="white")
-)
-
-TLP_GREEN = MarkingDefinition(
-                id="marking-definition--34098fce-860f-48ae-8e50-ebd3cc5e41da",
-                created="2017-01-20T00:00:00.000Z",
-                definition_type="tlp",
-                definition=TLPMarking(tlp="green")
-)
-
-TLP_AMBER = MarkingDefinition(
-                id="marking-definition--f88d31f6-486f-44da-b317-01333bde0b82",
-                created="2017-01-20T00:00:00.000Z",
-                definition_type="tlp",
-                definition=TLPMarking(tlp="amber")
-)
-
-TLP_RED = MarkingDefinition(
-                id="marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed",
-                created="2017-01-20T00:00:00.000Z",
-                definition_type="tlp",
-                definition=TLPMarking(tlp="red")
-)
diff --git a/stix2/other.py b/stix2/other.py
new file mode 100644
index 0000000..9b7f03a
--- /dev/null
+++ b/stix2/other.py
@@ -0,0 +1,124 @@
+"""STIX 2.0 Objects that are neither SDOs nor SROs"""
+
+from .base import _STIXBase
+from .properties import (IDProperty, ListProperty, Property, ReferenceProperty,
+                         SelectorProperty, StringProperty, TimestampProperty,
+                         TypeProperty)
+from .utils import get_dict, NOW
+
+
+class ExternalReference(_STIXBase):
+    _properties = {
+        'source_name': StringProperty(required=True),
+        'description': StringProperty(),
+        'url': StringProperty(),
+        'external_id': StringProperty(),
+    }
+
+
+class KillChainPhase(_STIXBase):
+    _properties = {
+        'kill_chain_name': StringProperty(required=True),
+        'phase_name': StringProperty(required=True),
+    }
+
+
+class GranularMarking(_STIXBase):
+    _properties = {
+        'marking_ref': ReferenceProperty(required=True, type="marking-definition"),
+        'selectors': ListProperty(SelectorProperty, required=True),
+    }
+
+
+class TLPMarking(_STIXBase):
+    # TODO: don't allow the creation of any other TLPMarkings than the ones below
+    _properties = {
+        'tlp': Property(required=True)
+    }
+
+
+class StatementMarking(_STIXBase):
+    _properties = {
+        'statement': StringProperty(required=True)
+    }
+
+    def __init__(self, statement=None, **kwargs):
+        # Allow statement as positional args.
+        if statement and not kwargs.get('statement'):
+            kwargs['statement'] = statement
+
+        super(StatementMarking, self).__init__(**kwargs)
+
+
+class MarkingProperty(Property):
+    """Represent the marking objects in the `definition` property of
+    marking-definition objects.
+    """
+
+    def clean(self, value):
+        if type(value) in [TLPMarking, StatementMarking]:
+            return value
+        else:
+            raise ValueError("must be a Statement or TLP Marking.")
+
+
+class MarkingDefinition(_STIXBase):
+    _type = 'marking-definition'
+    _properties = {
+        'created': TimestampProperty(default=lambda: NOW, required=True),
+        'external_references': ListProperty(ExternalReference),
+        'created_by_ref': ReferenceProperty(type="identity"),
+        'object_marking_refs': ListProperty(ReferenceProperty(type="marking-definition")),
+        'granular_markings': ListProperty(GranularMarking),
+        'type': TypeProperty(_type),
+        'id': IDProperty(_type),
+        'definition_type': StringProperty(required=True),
+        'definition': MarkingProperty(required=True),
+    }
+    marking_map = {
+        'tlp': TLPMarking,
+        'statement': StatementMarking,
+    }
+
+    def __init__(self, **kwargs):
+        if set(('definition_type', 'definition')).issubset(kwargs.keys()):
+            # Create correct marking type object
+            try:
+                marking_type = self.marking_map[kwargs['definition_type']]
+            except KeyError:
+                raise ValueError("definition_type must be a valid marking type")
+
+            if not isinstance(kwargs['definition'], marking_type):
+                defn = get_dict(kwargs['definition'])
+                kwargs['definition'] = marking_type(**defn)
+
+        super(MarkingDefinition, self).__init__(**kwargs)
+
+
+TLP_WHITE = MarkingDefinition(
+                id="marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9",
+                created="2017-01-20T00:00:00.000Z",
+                definition_type="tlp",
+                definition=TLPMarking(tlp="white")
+)
+
+TLP_GREEN = MarkingDefinition(
+                id="marking-definition--34098fce-860f-48ae-8e50-ebd3cc5e41da",
+                created="2017-01-20T00:00:00.000Z",
+                definition_type="tlp",
+                definition=TLPMarking(tlp="green")
+)
+
+TLP_AMBER = MarkingDefinition(
+                id="marking-definition--f88d31f6-486f-44da-b317-01333bde0b82",
+                created="2017-01-20T00:00:00.000Z",
+                definition_type="tlp",
+                definition=TLPMarking(tlp="amber")
+)
+
+TLP_RED = MarkingDefinition(
+                id="marking-definition--5e57c739-391a-4eb3-b6be-7d15ca92d5ed",
+                created="2017-01-20T00:00:00.000Z",
+                definition_type="tlp",
+                definition=TLPMarking(tlp="red")
+)
diff --git a/stix2/properties.py b/stix2/properties.py
index 88aa126..76fe31b 100644
--- a/stix2/properties.py
+++ b/stix2/properties.py
@@ -1,5 +1,13 @@
+import collections
+import datetime as dt
+import inspect
 import re
 import uuid
+
+from dateutil import parser
+import pytz
+from six import text_type
+
 from .base import _STIXBase
 
 
@@ -17,7 +25,7 @@ class Property(object):
         you to copy *all* values from an existing object to a new object), but
         if the user provides a value other than the `fixed` value, it will raise
         an error. This is semantically equivalent to defining both:
-        - a `validate()` function that checks if the value matches the fixed
+        - a `clean()` function that checks if the value matches the fixed
           value, and
         - a `default()` function that returns the fixed value.
         (Default: `None`)
@@ -25,15 +33,10 @@ class Property(object):
     Subclasses can also define the following functions.
 
     - `def clean(self, value) -> any:`
-        - Transform `value` into a valid value for this property. This should
-          raise a ValueError if such no such transformation is possible.
-    - `def validate(self, value) -> any:`
-        - check that `value` is valid for this property. This should return
-          a valid value (possibly modified) for this property, or raise a
-          ValueError if the value is not valid.
-          (Default: if `clean` is defined, it will attempt to call `clean` and
-          return the result or pass on a ValueError that `clean` raises. If
-          `clean` is not defined, this will return `value` unmodified).
+        - Return a value that is valid for this property. If `value` is not
+          valid for this property, this will attempt to transform it first. If
+          `value` is not valid and no such transformation is possible, it should
+          raise a ValueError.
     - `def default(self):`
         - provide a default value for this property.
         - `default()` can return the special value `NOW` to use the current
@@ -41,58 +44,94 @@ class Property(object):
             to use the same default value, so calling now() for each field--
             likely several microseconds apart-- does not work.
 
-    Subclasses can instead provide lambda functions for `clean`, and `default`
-    as keyword arguments. `validate` should not be provided as a lambda since
-    lambdas cannot raise their own exceptions.
+    Subclasses can instead provide a lambda function for `default` as a keyword
+    argument. `clean` should not be provided as a lambda since lambdas cannot
+    raise their own exceptions.
+
+    When instantiating Properties, `required` and `default` should not be used
+    together. `default` implies that the field is required in the specification
+    so this function will be used to supply a value if none is provided.
+    `required` means that the user must provide this; it is required in the
+    specification and we can't or don't want to create a default value.
     """
 
-    def _default_validate(self, value):
+    def _default_clean(self, value):
         if value != self._fixed_value:
             raise ValueError("must equal '{0}'.".format(self._fixed_value))
         return value
 
-    def __init__(self, required=False, fixed=None, clean=None, default=None, type=None):
+    def __init__(self, required=False, fixed=None, default=None, type=None):
         self.required = required
         self.type = type
         if fixed:
             self._fixed_value = fixed
-            self.validate = self._default_validate
+            self.clean = self._default_clean
             self.default = lambda: fixed
-        if clean:
-            self.clean = clean
         if default:
             self.default = default
 
     def clean(self, value):
-        raise NotImplementedError
+        return value
 
-    def validate(self, value):
-        try:
-            value = self.clean(value)
-        except NotImplementedError:
-            pass
+    def __call__(self, value=None):
+        """Used by ListProperty to handle lists that have been defined with
+        either a class or an instance.
+        """
         return value
 
 
 class ListProperty(Property):
 
-    def __init__(self, contained, required=False, element_type=None):
+    def __init__(self, contained, **kwargs):
         """
-        contained should be a type whose constructor creates an object from the value
+        Contained should be a function which returns an object from the value.
         """
-        self.contained = contained
-        self.element_type = element_type
-        super(ListProperty, self).__init__(required)
-
-    def validate(self, value):
-        # TODO: ensure iterable
-        result = []
-        for item in value:
-            result.append(self.contained(type=self.element_type).validate(item))
-        return result
+        if inspect.isclass(contained) and issubclass(contained, Property):
+            # If it's a class and not an instance, instantiate it so that
+            # clean() can be called on it, and ListProperty.clean() will
+            # use __call__ when it appends the item.
+            self.contained = contained()
+        else:
+            self.contained = contained
+        super(ListProperty, self).__init__(**kwargs)
 
     def clean(self, value):
-        return [self.contained(x) for x in value]
+        try:
+            iter(value)
+        except TypeError:
+            raise ValueError("must be an iterable.")
+
+        result = []
+        for item in value:
+            try:
+                valid = self.contained.clean(item)
+            except ValueError:
+                raise
+            except AttributeError:
+                # type of list has no clean() function (eg. built in Python types)
+                # TODO Should we raise an error here?
+                valid = item
+
+            if isinstance(valid, collections.Mapping):
+                result.append(self.contained(**valid))
+            else:
+                result.append(self.contained(valid))
+
+        # STIX spec forbids empty lists
+        if len(result) < 1:
+            raise ValueError("must not be empty.")
+
+        return result
+
+
+class StringProperty(Property):
+
+    def __init__(self, **kwargs):
+        self.string_type = text_type
+        super(StringProperty, self).__init__(**kwargs)
+
+    def clean(self, value):
+        return self.string_type(value)
 
 
 class TypeProperty(Property):
@@ -106,23 +145,72 @@ class IDProperty(Property):
         self.required_prefix = type + "--"
         super(IDProperty, self).__init__()
 
-    def validate(self, value):
-        # TODO: validate GUID as well
+    def clean(self, value):
         if not value.startswith(self.required_prefix):
             raise ValueError("must start with '{0}'.".format(self.required_prefix))
+        try:
+            uuid.UUID(value.split('--', 1)[1])
+        except Exception:
+            raise ValueError("must have a valid UUID after the prefix.")
         return value
 
     def default(self):
         return self.required_prefix + str(uuid.uuid4())
 
 
-class BooleanProperty(Property):
-    # TODO:  Consider coercing some values (like the strings "true" and "false")
+class IntegerProperty(Property):
 
-    def validate(self, value):
-        if not isinstance(value, bool):
-            raise ValueError("must be a boolean value.")
-        return value
+    def clean(self, value):
+        try:
+            return int(value)
+        except Exception:
+            raise ValueError("must be an integer.")
+
+
+class BooleanProperty(Property):
+
+    def clean(self, value):
+        if isinstance(value, bool):
+            return value
+
+        trues = ['true', 't']
+        falses = ['false', 'f']
+        try:
+            if value.lower() in trues:
+                return True
+            if value.lower() in falses:
+                return False
+        except AttributeError:
+            if value == 1:
+                return True
+            if value == 0:
+                return False
+
+        raise ValueError("must be a boolean value.")
+
+
+class TimestampProperty(Property):
+
+    def clean(self, value):
+        if isinstance(value, dt.date):
+            if hasattr(value, 'hour'):
+                return value
+            else:
+                # Add a time component
+                return dt.datetime.combine(value, dt.time(), tzinfo=pytz.utc)
+
+        # value isn't a date or datetime object so assume it's a string
+        try:
+            parsed = parser.parse(value)
+        except TypeError:
+            # Unknown format
+            raise ValueError("must be a datetime object, date object, or "
+                             "timestamp string in a recognizable format.")
+        if parsed.tzinfo:
+            return parsed.astimezone(pytz.utc)
+        else:
+            # Doesn't have timezone info in the string; assume UTC
+            return pytz.utc.localize(parsed)
 
 
 REF_REGEX = re.compile("^[a-z][a-z-]+[a-z]--[0-9a-fA-F]{8}-[0-9a-fA-F]{4}"
@@ -137,7 +225,7 @@ class ReferenceProperty(Property):
         self.type = type
         super(ReferenceProperty, self).__init__(required, type=type)
 
-    def validate(self, value):
+    def clean(self, value):
         if isinstance(value, _STIXBase):
             value = value.id
         if self.type:
@@ -156,7 +244,7 @@ class SelectorProperty(Property):
         # ignore type
         super(SelectorProperty, self).__init__()
 
-    def validate(self, value):
+    def clean(self, value):
         if not SELECTOR_REGEX.match(value):
             raise ValueError("must adhere to selector syntax.")
         return value
diff --git a/stix2/sdo.py b/stix2/sdo.py
index 978840f..693b750 100644
--- a/stix2/sdo.py
+++ b/stix2/sdo.py
@@ -2,7 +2,10 @@
 
 from .base import _STIXBase
 from .common import COMMON_PROPERTIES
-from .properties import IDProperty, TypeProperty, ListProperty, ReferenceProperty, Property
+from .other import KillChainPhase
+from .properties import (IDProperty, IntegerProperty, ListProperty, Property,
+                         ReferenceProperty, StringProperty, TimestampProperty,
+                         TypeProperty)
 from .utils import NOW
 
 
@@ -13,9 +16,9 @@ class AttackPattern(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'name': Property(required=True),
-        'description': Property(),
-        'kill_chain_phases': Property(),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'kill_chain_phases': ListProperty(KillChainPhase),
     })
 
 
@@ -26,12 +29,12 @@ class Campaign(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'name': Property(required=True),
-        'description': Property(),
-        'aliases': Property(),
-        'first_seen': Property(),
-        'last_seen': Property(),
-        'objective': Property(),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'aliases': ListProperty(StringProperty),
+        'first_seen': TimestampProperty(),
+        'last_seen': TimestampProperty(),
+        'objective': StringProperty(),
     })
 
 
@@ -42,8 +45,8 @@ class CourseOfAction(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'name': Property(required=True),
-        'description': Property(),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
     })
 
 
@@ -54,11 +57,12 @@ class Identity(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'name': Property(required=True),
-        'description': Property(),
-        'identity_class': Property(required=True),
-        'sectors': Property(),
-        'contact_information': Property(),
+        'labels': ListProperty(StringProperty),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'identity_class': StringProperty(required=True),
+        'sectors': ListProperty(StringProperty),
+        'contact_information': StringProperty(),
     })
 
 
@@ -69,13 +73,13 @@ class Indicator(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'labels': Property(required=True),
-        'name': Property(),
-        'description': Property(),
-        'pattern': Property(required=True),
-        'valid_from': Property(default=lambda: NOW),
-        'valid_until': Property(),
-        'kill_chain_phases': Property(),
+        'labels': ListProperty(StringProperty, required=True),
+        'name': StringProperty(),
+        'description': StringProperty(),
+        'pattern': StringProperty(required=True),
+        'valid_from': TimestampProperty(default=lambda: NOW),
+        'valid_until': TimestampProperty(),
+        'kill_chain_phases': ListProperty(KillChainPhase),
     })
 
 
@@ -86,15 +90,15 @@ class IntrusionSet(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'name': Property(required=True),
-        'description': Property(),
-        'aliases': Property(),
-        'first_seen': Property(),
-        'last_seen ': Property(),
-        'goals': Property(),
-        'resource_level': Property(),
-        'primary_motivation': Property(),
-        'secondary_motivations': Property(),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'aliases': ListProperty(StringProperty),
+        'first_seen': TimestampProperty(),
+        'last_seen ': TimestampProperty(),
+        'goals': ListProperty(StringProperty),
+        'resource_level': StringProperty(),
+        'primary_motivation': StringProperty(),
+        'secondary_motivations': ListProperty(StringProperty),
     })
 
 
@@ -105,10 +109,10 @@ class Malware(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'labels': Property(required=True),
-        'name': Property(required=True),
-        'description': Property(),
-        'kill_chain_phases': Property(),
+        'labels': ListProperty(StringProperty, required=True),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'kill_chain_phases': ListProperty(KillChainPhase),
     })
 
 
@@ -119,9 +123,9 @@ class ObservedData(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'first_observed': Property(),
-        'last_observed': Property(),
-        'number_observed': Property(),
+        'first_observed': TimestampProperty(required=True),
+        'last_observed': TimestampProperty(required=True),
+        'number_observed': IntegerProperty(required=True),
         'objects': Property(),
     })
 
@@ -133,10 +137,10 @@ class Report(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'labels': Property(required=True),
-        'name': Property(required=True),
-        'description': Property(),
-        'published': Property(),
+        'labels': ListProperty(StringProperty, required=True),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'published': TimestampProperty(),
         'object_refs': ListProperty(ReferenceProperty),
     })
 
@@ -148,17 +152,17 @@ class ThreatActor(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'labels': Property(required=True),
-        'name': Property(required=True),
-        'description': Property(),
-        'aliases': Property(),
-        'roles': Property(),
-        'goals': Property(),
-        'sophistication': Property(),
-        'resource_level': Property(),
-        'primary_motivation': Property(),
-        'secondary_motivations': Property(),
-        'personal_motivations': Property(),
+        'labels': ListProperty(StringProperty, required=True),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'aliases': ListProperty(StringProperty),
+        'roles': ListProperty(StringProperty),
+        'goals': ListProperty(StringProperty),
+        'sophistication': StringProperty(),
+        'resource_level': StringProperty(),
+        'primary_motivation': StringProperty(),
+        'secondary_motivations': ListProperty(StringProperty),
+        'personal_motivations': ListProperty(StringProperty),
     })
 
 
@@ -169,11 +173,11 @@ class Tool(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'labels': Property(required=True),
-        'name': Property(required=True),
-        'description': Property(),
-        'kill_chain_phases': Property(),
-        'tool_version': Property(),
+        'labels': ListProperty(StringProperty, required=True),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
+        'kill_chain_phases': ListProperty(KillChainPhase),
+        'tool_version': StringProperty(),
     })
 
 
@@ -184,6 +188,6 @@ class Vulnerability(_STIXBase):
     _properties.update({
         'type': TypeProperty(_type),
         'id': IDProperty(_type),
-        'name': Property(required=True),
-        'description': Property(),
+        'name': StringProperty(required=True),
+        'description': StringProperty(),
     })
diff --git a/stix2/sro.py b/stix2/sro.py
index 4fcae6c..c13fff3 100644
--- a/stix2/sro.py
+++ b/stix2/sro.py
@@ -2,7 +2,9 @@
 
 from .base import _STIXBase
 from .common import COMMON_PROPERTIES
-from .properties import IDProperty, TypeProperty, ReferenceProperty, ListProperty, Property
+from .properties import (IDProperty, IntegerProperty, ListProperty,
+                         ReferenceProperty, StringProperty, TimestampProperty,
+                         TypeProperty)
 
 
 class Relationship(_STIXBase):
@@ -12,8 +14,8 @@ class Relationship(_STIXBase):
     _properties.update({
         'id': IDProperty(_type),
         'type': TypeProperty(_type),
-        'relationship_type': Property(required=True),
-        'description': Property(),
+        'relationship_type': StringProperty(required=True),
+        'description': StringProperty(),
         'source_ref': ReferenceProperty(required=True),
         'target_ref': ReferenceProperty(required=True),
     })
@@ -41,13 +43,13 @@ class Sighting(_STIXBase):
     _properties.update({
         'id': IDProperty(_type),
         'type': TypeProperty(_type),
-        'first_seen': Property(),
-        'last_seen': Property(),
-        'count': Property(),
+        'first_seen': TimestampProperty(),
+        'last_seen': TimestampProperty(),
+        'count': IntegerProperty(),
         'sighting_of_ref': ReferenceProperty(required=True),
-        'observed_data_refs': ListProperty(ReferenceProperty, element_type="observed-data"),
-        'where_sighted_refs': ListProperty(ReferenceProperty, element_type="identity"),
-        'summary': Property(),
+        'observed_data_refs': ListProperty(ReferenceProperty(type="observed-data")),
+        'where_sighted_refs': ListProperty(ReferenceProperty(type="identity")),
+        'summary': StringProperty(),
     })
 
     # Explicitly define the first kwargs to make readable Sighting declarations.
diff --git a/stix2/test/constants.py b/stix2/test/constants.py
index 6d88a84..1c8ae2b 100644
--- a/stix2/test/constants.py
+++ b/stix2/test/constants.py
@@ -4,11 +4,21 @@ import pytz
 
 FAKE_TIME = dt.datetime(2017, 1, 1, 12, 34, 56, tzinfo=pytz.utc)
 
+ATTACK_PATTERN_ID = "attack-pattern--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061"
+CAMPAIGN_ID = "campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f"
+COURSE_OF_ACTION_ID = "course-of-action--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f"
+IDENTITY_ID = "identity--311b2d2d-f010-5473-83ec-1edf84858f4c"
 INDICATOR_ID = "indicator--01234567-89ab-cdef-0123-456789abcdef"
+INTRUSION_SET_ID = "intrusion-set--4e78f46f-a023-4e5f-bc24-71b3ca22ec29"
 MALWARE_ID = "malware--fedcba98-7654-3210-fedc-ba9876543210"
+MARKING_DEFINITION_ID = "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9"
+OBSERVED_DATA_ID = "observed-data--b67d30ff-02ac-498a-92f9-32f845f448cf"
+REPORT_ID = "report--84e4d88f-44ea-4bcd-bbf3-b2c1c320bcb3"
 RELATIONSHIP_ID = "relationship--00000000-1111-2222-3333-444444444444"
-IDENTITY_ID = "identity--d4d765ce-cff7-40e8-b7a6-e205d005ac2c"
+THREAT_ACTOR_ID = "threat-actor--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f"
+TOOL_ID = "tool--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f"
 SIGHTING_ID = "sighting--bfbc19db-ec35-4e45-beed-f8bde2a772fb"
+VULNERABILITY_ID = "vulnerability--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061"
 
 # Minimum required args for an Indicator instance
 INDICATOR_KWARGS = dict(
diff --git a/stix2/test/test_attack_pattern.py b/stix2/test/test_attack_pattern.py
index a9d53b6..c0891a5 100644
--- a/stix2/test/test_attack_pattern.py
+++ b/stix2/test/test_attack_pattern.py
@@ -1,16 +1,22 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import ATTACK_PATTERN_ID
+
 EXPECTED = """{
-    "created": "2016-05-12T08:17:27.000Z",
+    "created": "2016-05-12T08:17:27Z",
     "description": "...",
     "external_references": [
         {
-            "id": "CAPEC-163",
+            "external_id": "CAPEC-163",
             "source_name": "capec"
         }
     ],
     "id": "attack-pattern--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061",
-    "modified": "2016-05-12T08:17:27.000Z",
+    "modified": "2016-05-12T08:17:27Z",
     "name": "Spear Phishing",
     "type": "attack-pattern"
 }"""
@@ -19,12 +25,12 @@ EXPECTED = """{
 def test_attack_pattern_example():
     ap = stix2.AttackPattern(
         id="attack-pattern--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061",
-        created="2016-05-12T08:17:27.000Z",
-        modified="2016-05-12T08:17:27.000Z",
+        created="2016-05-12T08:17:27Z",
+        modified="2016-05-12T08:17:27Z",
         name="Spear Phishing",
         external_references=[{
             "source_name": "capec",
-            "id": "CAPEC-163"
+            "external_id": "CAPEC-163"
         }],
         description="...",
     )
@@ -32,4 +38,33 @@ def test_attack_pattern_example():
     assert str(ap) == EXPECTED
 
 
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "type": "attack-pattern",
+        "id": "attack-pattern--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061",
+        "created": "2016-05-12T08:17:27Z",
+        "modified": "2016-05-12T08:17:27Z",
+        "description": "...",
+        "external_references": [
+            {
+                "external_id": "CAPEC-163",
+                "source_name": "capec"
+            }
+        ],
+        "name": "Spear Phishing",
+    },
+])
+def test_parse_attack_pattern(data):
+    ap = stix2.parse(data)
+
+    assert ap.type == 'attack-pattern'
+    assert ap.id == ATTACK_PATTERN_ID
+    assert ap.created == dt.datetime(2016, 5, 12, 8, 17, 27, tzinfo=pytz.utc)
+    assert ap.modified == dt.datetime(2016, 5, 12, 8, 17, 27, tzinfo=pytz.utc)
+    assert ap.description == "..."
+    assert ap.external_references[0].external_id == 'CAPEC-163'
+    assert ap.external_references[0].source_name == 'capec'
+    assert ap.name == "Spear Phishing"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_campaign.py b/stix2/test/test_campaign.py
index ce68946..7f6c4e6 100644
--- a/stix2/test/test_campaign.py
+++ b/stix2/test/test_campaign.py
@@ -1,11 +1,17 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import CAMPAIGN_ID
+
 EXPECTED = """{
-    "created": "2016-04-06T20:03:00.000Z",
+    "created": "2016-04-06T20:03:00Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "description": "Campaign by Green Group against a series of targets in the financial services sector.",
     "id": "campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
-    "modified": "2016-04-06T20:03:00.000Z",
+    "modified": "2016-04-06T20:03:00Z",
     "name": "Green Group Attacks Against Finance",
     "type": "campaign"
 }"""
@@ -15,12 +21,36 @@ def test_campaign_example():
     campaign = stix2.Campaign(
         id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T20:03:00.000Z",
-        modified="2016-04-06T20:03:00.000Z",
+        created="2016-04-06T20:03:00Z",
+        modified="2016-04-06T20:03:00Z",
         name="Green Group Attacks Against Finance",
         description="Campaign by Green Group against a series of targets in the financial services sector."
     )
 
     assert str(campaign) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "type": "campaign",
+        "id": "campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        "created": "2016-04-06T20:03:00Z",
+        "modified": "2016-04-06T20:03:00Z",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "description": "Campaign by Green Group against a series of targets in the financial services sector.",
+        "name": "Green Group Attacks Against Finance",
+    },
+])
+def test_parse_campaign(data):
+    cmpn = stix2.parse(data)
+
+    assert cmpn.type == 'campaign'
+    assert cmpn.id == CAMPAIGN_ID
+    assert cmpn.created == dt.datetime(2016, 4, 6, 20, 3, 0, tzinfo=pytz.utc)
+    assert cmpn.modified == dt.datetime(2016, 4, 6, 20, 3, 0, tzinfo=pytz.utc)
+    assert cmpn.created_by_ref == "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff"
+    assert cmpn.description == "Campaign by Green Group against a series of targets in the financial services sector."
+    assert cmpn.name == "Green Group Attacks Against Finance"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_course_of_action.py b/stix2/test/test_course_of_action.py
index 8c64cde..f566e10 100644
--- a/stix2/test/test_course_of_action.py
+++ b/stix2/test/test_course_of_action.py
@@ -1,11 +1,17 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import COURSE_OF_ACTION_ID
+
 EXPECTED = """{
-    "created": "2016-04-06T20:03:48.000Z",
+    "created": "2016-04-06T20:03:48Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "description": "This is how to add a filter rule to block inbound access to TCP port 80 to the existing UDP 1434 filter ...",
     "id": "course-of-action--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
-    "modified": "2016-04-06T20:03:48.000Z",
+    "modified": "2016-04-06T20:03:48Z",
     "name": "Add TCP port 80 Filter Rule to the existing Block UDP 1434 Filter",
     "type": "course-of-action"
 }"""
@@ -15,12 +21,36 @@ def test_course_of_action_example():
     coa = stix2.CourseOfAction(
         id="course-of-action--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T20:03:48.000Z",
-        modified="2016-04-06T20:03:48.000Z",
+        created="2016-04-06T20:03:48Z",
+        modified="2016-04-06T20:03:48Z",
         name="Add TCP port 80 Filter Rule to the existing Block UDP 1434 Filter",
         description="This is how to add a filter rule to block inbound access to TCP port 80 to the existing UDP 1434 filter ..."
     )
 
     assert str(coa) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "created": "2016-04-06T20:03:48Z",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "description": "This is how to add a filter rule to block inbound access to TCP port 80 to the existing UDP 1434 filter ...",
+        "id": "course-of-action--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        "modified": "2016-04-06T20:03:48Z",
+        "name": "Add TCP port 80 Filter Rule to the existing Block UDP 1434 Filter",
+        "type": "course-of-action"
+    },
+])
+def test_parse_course_of_action(data):
+    coa = stix2.parse(data)
+
+    assert coa.type == 'course-of-action'
+    assert coa.id == COURSE_OF_ACTION_ID
+    assert coa.created == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert coa.modified == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert coa.created_by_ref == "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff"
+    assert coa.description == "This is how to add a filter rule to block inbound access to TCP port 80 to the existing UDP 1434 filter ..."
+    assert coa.name == "Add TCP port 80 Filter Rule to the existing Block UDP 1434 Filter"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_external_reference.py b/stix2/test/test_external_reference.py
index 52e21cc..f8d9b66 100644
--- a/stix2/test/test_external_reference.py
+++ b/stix2/test/test_external_reference.py
@@ -1,7 +1,8 @@
 """Tests for stix.ExternalReference"""
 
-import pytest
+import re
 
+import pytest
 import stix2
 
 VERIS = """{
@@ -34,7 +35,7 @@ def test_external_reference_capec():
     )
 
     assert str(ref) == CAPEC
-    assert repr(ref) == "ExternalReference(external_id='CAPEC-550', source_name='capec')"
+    assert re.match("ExternalReference\(external_id=u?'CAPEC-550', source_name=u?'capec'\)", repr(ref))
 
 
 CAPEC_URL = """{
@@ -101,7 +102,7 @@ def test_external_reference_offline():
     )
 
     assert str(ref) == OFFLINE
-    assert repr(ref) == "ExternalReference(description='Threat report', source_name='ACME Threat Intel')"
+    assert re.match("ExternalReference\(description=u?'Threat report', source_name=u?'ACME Threat Intel'\)", repr(ref))
     # Yikes! This works
     assert eval("stix2." + repr(ref)) == ref
 
diff --git a/stix2/test/test_identity.py b/stix2/test/test_identity.py
index 632f229..41c87bb 100644
--- a/stix2/test/test_identity.py
+++ b/stix2/test/test_identity.py
@@ -1,10 +1,16 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import IDENTITY_ID
+
 EXPECTED = """{
-    "created": "2015-12-21T19:59:11.000Z",
+    "created": "2015-12-21T19:59:11Z",
     "id": "identity--311b2d2d-f010-5473-83ec-1edf84858f4c",
     "identity_class": "individual",
-    "modified": "2015-12-21T19:59:11.000Z",
+    "modified": "2015-12-21T19:59:11Z",
     "name": "John Smith",
     "type": "identity"
 }"""
@@ -13,12 +19,33 @@ EXPECTED = """{
 def test_identity_example():
     report = stix2.Identity(
         id="identity--311b2d2d-f010-5473-83ec-1edf84858f4c",
-        created="2015-12-21T19:59:11.000Z",
-        modified="2015-12-21T19:59:11.000Z",
+        created="2015-12-21T19:59:11Z",
+        modified="2015-12-21T19:59:11Z",
         name="John Smith",
         identity_class="individual",
     )
 
     assert str(report) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "created": "2015-12-21T19:59:11Z",
+        "id": "identity--311b2d2d-f010-5473-83ec-1edf84858f4c",
+        "identity_class": "individual",
+        "modified": "2015-12-21T19:59:11Z",
+        "name": "John Smith",
+        "type": "identity"
+    },
+])
+def test_parse_identity(data):
+    identity = stix2.parse(data)
+
+    assert identity.type == 'identity'
+    assert identity.id == IDENTITY_ID
+    assert identity.created == dt.datetime(2015, 12, 21, 19, 59, 11, tzinfo=pytz.utc)
+    assert identity.modified == dt.datetime(2015, 12, 21, 19, 59, 11, tzinfo=pytz.utc)
+    assert identity.name == "John Smith"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_indicator.py b/stix2/test/test_indicator.py
index a941bc9..1c2b610 100644
--- a/stix2/test/test_indicator.py
+++ b/stix2/test/test_indicator.py
@@ -1,8 +1,8 @@
 import datetime as dt
+import re
 
 import pytest
 import pytz
-
 import stix2
 
 from .constants import FAKE_TIME, INDICATOR_ID, INDICATOR_KWARGS
@@ -45,7 +45,8 @@ def test_indicator_with_all_required_fields():
     )
 
     assert str(ind) == EXPECTED_INDICATOR
-    assert repr(ind) == EXPECTED_INDICATOR_REPR
+    rep = re.sub(r"(\[|=| )u('|\"|\\\'|\\\")", r"\g<1>\g<2>", repr(ind))
+    assert rep == EXPECTED_INDICATOR_REPR
 
 
 def test_indicator_autogenerated_fields(indicator):
@@ -116,12 +117,11 @@ def test_indicator_created_ref_invalid_format():
 
 def test_indicator_revoked_invalid():
     with pytest.raises(stix2.exceptions.InvalidValueError) as excinfo:
-        stix2.Indicator(revoked='false', **INDICATOR_KWARGS)
+        stix2.Indicator(revoked='no', **INDICATOR_KWARGS)
 
     assert excinfo.value.cls == stix2.Indicator
     assert excinfo.value.prop_name == "revoked"
     assert excinfo.value.reason == "must be a boolean value."
-    assert str(excinfo.value) == "Invalid value for Indicator 'revoked': must be a boolean value."
 
 
 def test_cannot_assign_to_indicator_attributes(indicator):
@@ -145,3 +145,29 @@ def test_created_modified_time_are_identical_by_default():
     ind = stix2.Indicator(**INDICATOR_KWARGS)
 
     assert ind.created == ind.modified
+
+
+@pytest.mark.parametrize("data", [
+    EXPECTED_INDICATOR,
+    {
+        "type": "indicator",
+        "id": "indicator--01234567-89ab-cdef-0123-456789abcdef",
+        "created": "2017-01-01T00:00:01Z",
+        "modified": "2017-01-01T00:00:01Z",
+        "labels": [
+            "malicious-activity"
+        ],
+        "pattern": "[file:hashes.MD5 = 'd41d8cd98f00b204e9800998ecf8427e']",
+        "valid_from": "1970-01-01T00:00:01Z"
+    },
+])
+def test_parse_indicator(data):
+    idctr = stix2.parse(data)
+
+    assert idctr.type == 'indicator'
+    assert idctr.id == INDICATOR_ID
+    assert idctr.created == dt.datetime(2017, 1, 1, 0, 0, 1, tzinfo=pytz.utc)
+    assert idctr.modified == dt.datetime(2017, 1, 1, 0, 0, 1, tzinfo=pytz.utc)
+    assert idctr.valid_from == dt.datetime(1970, 1, 1, 0, 0, 1, tzinfo=pytz.utc)
+    assert idctr.labels[0] == "malicious-activity"
+    assert idctr.pattern == "[file:hashes.MD5 = 'd41d8cd98f00b204e9800998ecf8427e']"
diff --git a/stix2/test/test_intrusion_set.py b/stix2/test/test_intrusion_set.py
index ba158d7..19fb641 100644
--- a/stix2/test/test_intrusion_set.py
+++ b/stix2/test/test_intrusion_set.py
@@ -1,10 +1,16 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import INTRUSION_SET_ID
+
 EXPECTED = """{
     "aliases": [
         "Zookeeper"
     ],
-    "created": "2016-04-06T20:03:48.000Z",
+    "created": "2016-04-06T20:03:48Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "description": "Incidents usually feature a shared TTP of a bobcat being released...",
     "goals": [
@@ -13,7 +19,7 @@ EXPECTED = """{
         "damage"
     ],
     "id": "intrusion-set--4e78f46f-a023-4e5f-bc24-71b3ca22ec29",
-    "modified": "2016-04-06T20:03:48.000Z",
+    "modified": "2016-04-06T20:03:48Z",
     "name": "Bobcat Breakin",
     "type": "intrusion-set"
 }"""
@@ -23,8 +29,8 @@ def test_intrusion_set_example():
     intrusion_set = stix2.IntrusionSet(
         id="intrusion-set--4e78f46f-a023-4e5f-bc24-71b3ca22ec29",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T20:03:48.000Z",
-        modified="2016-04-06T20:03:48.000Z",
+        created="2016-04-06T20:03:48Z",
+        modified="2016-04-06T20:03:48Z",
         name="Bobcat Breakin",
         description="Incidents usually feature a shared TTP of a bobcat being released...",
         aliases=["Zookeeper"],
@@ -33,4 +39,37 @@ def test_intrusion_set_example():
 
     assert str(intrusion_set) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "aliases": [
+            "Zookeeper"
+        ],
+        "created": "2016-04-06T20:03:48Z",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "description": "Incidents usually feature a shared TTP of a bobcat being released...",
+        "goals": [
+            "acquisition-theft",
+            "harassment",
+            "damage"
+        ],
+        "id": "intrusion-set--4e78f46f-a023-4e5f-bc24-71b3ca22ec29",
+        "modified": "2016-04-06T20:03:48Z",
+        "name": "Bobcat Breakin",
+        "type": "intrusion-set"
+    },
+])
+def test_parse_intrusion_set(data):
+    intset = stix2.parse(data)
+
+    assert intset.type == "intrusion-set"
+    assert intset.id == INTRUSION_SET_ID
+    assert intset.created == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert intset.modified == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert intset.goals == ["acquisition-theft", "harassment", "damage"]
+    assert intset.aliases == ["Zookeeper"]
+    assert intset.description == "Incidents usually feature a shared TTP of a bobcat being released..."
+    assert intset.name == "Bobcat Breakin"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_malware.py b/stix2/test/test_malware.py
index f0431c4..edc35b6 100644
--- a/stix2/test/test_malware.py
+++ b/stix2/test/test_malware.py
@@ -1,8 +1,8 @@
 import datetime as dt
+import re
 
 import pytest
 import pytz
-
 import stix2
 
 from .constants import FAKE_TIME, MALWARE_ID, MALWARE_KWARGS
@@ -102,3 +102,61 @@ def test_invalid_kwarg_to_malware():
     assert excinfo.value.cls == stix2.Malware
     assert excinfo.value.fields == ['my_custom_property']
     assert str(excinfo.value) == "Unexpected field(s) for Malware: (my_custom_property)."
+
+
+@pytest.mark.parametrize("data", [
+    EXPECTED_MALWARE,
+    {
+        "type": "malware",
+        "id": "malware--fedcba98-7654-3210-fedc-ba9876543210",
+        "created": "2016-05-12T08:17:27Z",
+        "modified": "2016-05-12T08:17:27Z",
+        "labels": ["ransomware"],
+        "name": "Cryptolocker",
+    },
+])
+def test_parse_malware(data):
+    mal = stix2.parse(data)
+
+    assert mal.type == 'malware'
+    assert mal.id == MALWARE_ID
+    assert mal.created == dt.datetime(2016, 5, 12, 8, 17, 27, tzinfo=pytz.utc)
+    assert mal.modified == dt.datetime(2016, 5, 12, 8, 17, 27, tzinfo=pytz.utc)
+    assert mal.labels == ['ransomware']
+    assert mal.name == "Cryptolocker"
+
+
+def test_parse_malware_invalid_labels():
+    data = re.compile('\[.+\]', re.DOTALL).sub('1', EXPECTED_MALWARE)
+    with pytest.raises(ValueError) as excinfo:
+        stix2.parse(data)
+    assert "Invalid value for Malware 'labels'" in str(excinfo.value)
+
+
+def test_parse_malware_kill_chain_phases():
+    kill_chain = """
+      "kill_chain_phases": [
+        {
+          "kill_chain_name": "lockheed-martin-cyber-kill-chain",
+          "phase_name": "reconnaissance"
+        }
+      ]"""
+    data = EXPECTED_MALWARE.replace('malware"', 'malware",%s' % kill_chain)
+    mal = stix2.parse(data)
+    assert mal.kill_chain_phases[0].kill_chain_name == "lockheed-martin-cyber-kill-chain"
+    assert mal.kill_chain_phases[0].phase_name == "reconnaissance"
+    assert mal['kill_chain_phases'][0]['kill_chain_name'] == "lockheed-martin-cyber-kill-chain"
+    assert mal['kill_chain_phases'][0]['phase_name'] == "reconnaissance"
+
+
+def test_parse_malware_clean_kill_chain_phases():
+    kill_chain = """
+      "kill_chain_phases": [
+        {
+          "kill_chain_name": "lockheed-martin-cyber-kill-chain",
+          "phase_name": 1
+        }
+      ]"""
+    data = EXPECTED_MALWARE.replace('malware"', 'malware",%s' % kill_chain)
+    mal = stix2.parse(data)
+    assert mal['kill_chain_phases'][0]['phase_name'] == "1"
diff --git a/stix2/test/test_markings.py b/stix2/test/test_markings.py
index 56ce771..b3cc479 100644
--- a/stix2/test/test_markings.py
+++ b/stix2/test/test_markings.py
@@ -1,9 +1,14 @@
-import stix2
-from stix2.markings import TLP_WHITE
+import datetime as dt
+
 import pytest
+import pytz
+import stix2
+from stix2.other import TLP_WHITE
+
+from .constants import MARKING_DEFINITION_ID
 
 EXPECTED_TLP_MARKING_DEFINITION = """{
-    "created": "2017-01-20T00:00:00.000Z",
+    "created": "2017-01-20T00:00:00Z",
     "definition": {
         "tlp": "white"
     },
@@ -13,7 +18,7 @@ EXPECTED_TLP_MARKING_DEFINITION = """{
 }"""
 
 EXPECTED_STATEMENT_MARKING_DEFINITION = """{
-    "created": "2017-01-20T00:00:00.000Z",
+    "created": "2017-01-20T00:00:00Z",
     "definition": {
         "statement": "Copyright 2016, Example Corp"
     },
@@ -33,7 +38,7 @@ EXPECTED_GRANULAR_MARKING = """{
 }"""
 
 EXPECTED_CAMPAIGN_WITH_GRANULAR_MARKINGS = """{
-    "created": "2016-04-06T20:03:00.000Z",
+    "created": "2016-04-06T20:03:00Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "description": "Campaign by Green Group against a series of targets in the financial services sector.",
     "granular_markings": [
@@ -45,7 +50,7 @@ EXPECTED_CAMPAIGN_WITH_GRANULAR_MARKINGS = """{
         }
     ],
     "id": "campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
-    "modified": "2016-04-06T20:03:00.000Z",
+    "modified": "2016-04-06T20:03:00Z",
     "name": "Green Group Attacks Against Finance",
     "type": "campaign"
 }"""
@@ -103,8 +108,8 @@ def test_campaign_with_granular_markings_example():
     campaign = stix2.Campaign(
         id="campaign--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T20:03:00.000Z",
-        modified="2016-04-06T20:03:00.000Z",
+        created="2016-04-06T20:03:00Z",
+        modified="2016-04-06T20:03:00Z",
         name="Green Group Attacks Against Finance",
         description="Campaign by Green Group against a series of targets in the financial services sector.",
         granular_markings=[
@@ -115,4 +120,27 @@ def test_campaign_with_granular_markings_example():
     print(str(campaign))
     assert str(campaign) == EXPECTED_CAMPAIGN_WITH_GRANULAR_MARKINGS
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED_TLP_MARKING_DEFINITION,
+    {
+        "id": "marking-definition--613f2e26-407d-48c7-9eca-b8e91df99dc9",
+        "type": "marking-definition",
+        "created": "2017-01-20T00:00:00Z",
+        "definition": {
+            "tlp": "white"
+        },
+        "definition_type": "tlp",
+    },
+])
+def test_parse_marking_definition(data):
+    gm = stix2.parse(data)
+
+    assert gm.type == 'marking-definition'
+    assert gm.id == MARKING_DEFINITION_ID
+    assert gm.created == dt.datetime(2017, 1, 20, 0, 0, 0, tzinfo=pytz.utc)
+    assert gm.definition.tlp == "white"
+    assert gm.definition_type == "tlp"
+
+
 # TODO: Add other examples
diff --git a/stix2/test/test_observed_data.py b/stix2/test/test_observed_data.py
index 6fd95a2..52dc15b 100644
--- a/stix2/test/test_observed_data.py
+++ b/stix2/test/test_observed_data.py
@@ -1,12 +1,18 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import OBSERVED_DATA_ID
+
 EXPECTED = """{
-    "created": "2016-04-06T19:58:16.000Z",
+    "created": "2016-04-06T19:58:16Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "first_observed": "2015-12-21T19:00:00Z",
     "id": "observed-data--b67d30ff-02ac-498a-92f9-32f845f448cf",
     "last_observed": "2015-12-21T19:00:00Z",
-    "modified": "2016-04-06T19:58:16.000Z",
+    "modified": "2016-04-06T19:58:16Z",
     "number_observed": 50,
     "objects": {
         "0": {
@@ -21,8 +27,8 @@ def test_observed_data_example():
     observed_data = stix2.ObservedData(
         id="observed-data--b67d30ff-02ac-498a-92f9-32f845f448cf",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T19:58:16.000Z",
-        modified="2016-04-06T19:58:16.000Z",
+        created="2016-04-06T19:58:16Z",
+        modified="2016-04-06T19:58:16Z",
         first_observed="2015-12-21T19:00:00Z",
         last_observed="2015-12-21T19:00:00Z",
         number_observed=50,
@@ -35,4 +41,35 @@ def test_observed_data_example():
 
     assert str(observed_data) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "type": "observed-data",
+        "id": "observed-data--b67d30ff-02ac-498a-92f9-32f845f448cf",
+        "created": "2016-04-06T19:58:16Z",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "first_observed": "2015-12-21T19:00:00Z",
+        "last_observed": "2015-12-21T19:00:00Z",
+        "modified": "2016-04-06T19:58:16Z",
+        "number_observed": 50,
+        "objects": {
+            "0": {
+                "type": "file"
+            }
+        }
+    },
+])
+def test_parse_observed_data(data):
+    odata = stix2.parse(data)
+
+    assert odata.type == 'observed-data'
+    assert odata.id == OBSERVED_DATA_ID
+    assert odata.created == dt.datetime(2016, 4, 6, 19, 58, 16, tzinfo=pytz.utc)
+    assert odata.modified == dt.datetime(2016, 4, 6, 19, 58, 16, tzinfo=pytz.utc)
+    assert odata.first_observed == dt.datetime(2015, 12, 21, 19, 0, 0, tzinfo=pytz.utc)
+    assert odata.last_observed == dt.datetime(2015, 12, 21, 19, 0, 0, tzinfo=pytz.utc)
+    assert odata.created_by_ref == "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff"
+    # assert odata.objects["0"].type == "file"  # TODO
+
 # TODO: Add other examples
diff --git a/stix2/test/test_properties.py b/stix2/test/test_properties.py
index f3c4ff9..e83b2fc 100644
--- a/stix2/test/test_properties.py
+++ b/stix2/test/test_properties.py
@@ -1,7 +1,9 @@
 import pytest
 
-from stix2.properties import (Property, BooleanProperty, IDProperty,
-                              ReferenceProperty, TypeProperty)
+from stix2.properties import (BooleanProperty, IDProperty, IntegerProperty,
+                              ListProperty, Property, ReferenceProperty,
+                              StringProperty, TimestampProperty, TypeProperty)
+from .constants import FAKE_TIME
 
 
 def test_property():
@@ -10,10 +12,10 @@ def test_property():
     assert p.required is False
 
 
-def test_basic_validate():
+def test_basic_clean():
     class Prop(Property):
 
-        def validate(self, value):
+        def clean(self, value):
             if value == 42:
                 return value
             else:
@@ -21,9 +23,9 @@ def test_basic_validate():
 
     p = Prop()
 
-    assert p.validate(42) == 42
+    assert p.clean(42) == 42
     with pytest.raises(ValueError):
-        p.validate(41)
+        p.clean(41)
 
 
 def test_default_field():
@@ -40,48 +42,132 @@ def test_default_field():
 def test_fixed_property():
     p = Property(fixed="2.0")
 
-    assert p.validate("2.0")
+    assert p.clean("2.0")
     with pytest.raises(ValueError):
-        assert p.validate("x") is False
+        assert p.clean("x") is False
     with pytest.raises(ValueError):
-        assert p.validate(2.0) is False
+        assert p.clean(2.0) is False
 
     assert p.default() == "2.0"
-    assert p.validate(p.default())
+    assert p.clean(p.default())
+
+
+def test_list_property():
+    p = ListProperty(StringProperty)
+
+    assert p.clean(['abc', 'xyz'])
+    with pytest.raises(ValueError):
+        p.clean([])
+
+
+def test_string_property():
+    prop = StringProperty()
+
+    assert prop.clean('foobar')
+    assert prop.clean(1)
+    assert prop.clean([1, 2, 3])
 
 
 def test_type_property():
     prop = TypeProperty('my-type')
 
-    assert prop.validate('my-type')
+    assert prop.clean('my-type')
     with pytest.raises(ValueError):
-        prop.validate('not-my-type')
-    assert prop.validate(prop.default())
+        prop.clean('not-my-type')
+    assert prop.clean(prop.default())
 
 
 def test_id_property():
     idprop = IDProperty('my-type')
 
-    assert idprop.validate('my-type--90aaca8a-1110-5d32-956d-ac2f34a1bd8c')
+    assert idprop.clean('my-type--90aaca8a-1110-5d32-956d-ac2f34a1bd8c')
+    with pytest.raises(ValueError) as excinfo:
+        idprop.clean('not-my-type--90aaca8a-1110-5d32-956d-ac2f34a1bd8c')
+    assert str(excinfo.value) == "must start with 'my-type--'."
+    with pytest.raises(ValueError) as excinfo:
+        idprop.clean('my-type--foo')
+    assert str(excinfo.value) == "must have a valid UUID after the prefix."
+
+    assert idprop.clean(idprop.default())
+
+
+@pytest.mark.parametrize("value", [
+    2,
+    -1,
+    3.14,
+    False,
+])
+def test_integer_property_valid(value):
+    int_prop = IntegerProperty()
+    assert int_prop.clean(value) is not None
+
+
+@pytest.mark.parametrize("value", [
+    "something",
+    StringProperty(),
+])
+def test_integer_property_invalid(value):
+    int_prop = IntegerProperty()
     with pytest.raises(ValueError):
-        idprop.validate('not-my-type--90aaca8a-1110-5d32-956d-ac2f34a1bd8c')
-    assert idprop.validate(idprop.default())
+        int_prop.clean(value)
 
 
-def test_boolean_property():
+@pytest.mark.parametrize("value", [
+    True,
+    False,
+    'True',
+    'False',
+    'true',
+    'false',
+    'TRUE',
+    'FALSE',
+    'T',
+    'F',
+    't',
+    'f',
+    1,
+    0,
+])
+def test_boolean_property_valid(value):
     bool_prop = BooleanProperty()
 
-    assert bool_prop.validate(True) is not None
-    assert bool_prop.validate(False) is not None
-    for invalid in ('true', 'false', "T", "F", 1, 0):
-        print(invalid)
-        with pytest.raises(ValueError):
-            bool_prop.validate(invalid)
+    assert bool_prop.clean(value) is not None
+
+
+@pytest.mark.parametrize("value", [
+    'abc',
+    ['false'],
+    {'true': 'true'},
+    2,
+    -1,
+])
+def test_boolean_property_invalid(value):
+    bool_prop = BooleanProperty()
+    with pytest.raises(ValueError):
+        bool_prop.clean(value)
 
 
 def test_reference_property():
     ref_prop = ReferenceProperty()
 
-    assert ref_prop.validate("my-type--3a331bfe-0566-55e1-a4a0-9a2cd355a300")
+    assert ref_prop.clean("my-type--3a331bfe-0566-55e1-a4a0-9a2cd355a300")
     with pytest.raises(ValueError):
-        ref_prop.validate("foo")
+        ref_prop.clean("foo")
+
+
+@pytest.mark.parametrize("value", [
+    '2017-01-01T12:34:56Z',
+    '2017-01-01 12:34:56',
+    'Jan 1 2017 12:34:56',
+])
+def test_timestamp_property_valid(value):
+    ts_prop = TimestampProperty()
+    assert ts_prop.clean(value) == FAKE_TIME
+
+
+def test_timestamp_property_invalid():
+    ts_prop = TimestampProperty()
+    with pytest.raises(ValueError):
+        ts_prop.clean(1)
+    with pytest.raises(ValueError):
+        ts_prop.clean("someday sometime")
diff --git a/stix2/test/test_relationship.py b/stix2/test/test_relationship.py
index f250ec8..72e659c 100644
--- a/stix2/test/test_relationship.py
+++ b/stix2/test/test_relationship.py
@@ -133,3 +133,27 @@ def test_create_relationship_with_positional_args(indicator, malware):
     assert rel.source_ref == 'indicator--00000000-0000-0000-0000-000000000001'
     assert rel.target_ref == 'malware--00000000-0000-0000-0000-000000000002'
     assert rel.id == 'relationship--00000000-0000-0000-0000-000000000003'
+
+
+@pytest.mark.parametrize("data", [
+    EXPECTED_RELATIONSHIP,
+    {
+        "created": "2016-04-06T20:06:37Z",
+        "id": "relationship--00000000-1111-2222-3333-444444444444",
+        "modified": "2016-04-06T20:06:37Z",
+        "relationship_type": "indicates",
+        "source_ref": "indicator--01234567-89ab-cdef-0123-456789abcdef",
+        "target_ref": "malware--fedcba98-7654-3210-fedc-ba9876543210",
+        "type": "relationship"
+    },
+])
+def test_parse_relationship(data):
+    rel = stix2.parse(data)
+
+    assert rel.type == 'relationship'
+    assert rel.id == RELATIONSHIP_ID
+    assert rel.created == dt.datetime(2016, 4, 6, 20, 6, 37, tzinfo=pytz.utc)
+    assert rel.modified == dt.datetime(2016, 4, 6, 20, 6, 37, tzinfo=pytz.utc)
+    assert rel.relationship_type == "indicates"
+    assert rel.source_ref == "indicator--01234567-89ab-cdef-0123-456789abcdef"
+    assert rel.target_ref == "malware--fedcba98-7654-3210-fedc-ba9876543210"
diff --git a/stix2/test/test_report.py b/stix2/test/test_report.py
index 1783255..46a0a16 100644
--- a/stix2/test/test_report.py
+++ b/stix2/test/test_report.py
@@ -1,23 +1,27 @@
-import stix2
+import datetime as dt
+
 import pytest
-from .constants import INDICATOR_KWARGS
+import pytz
+import stix2
+
+from .constants import INDICATOR_KWARGS, REPORT_ID
 
 EXPECTED = """{
-    "created": "2015-12-21T19:59:11.000Z",
+    "created": "2015-12-21T19:59:11Z",
     "created_by_ref": "identity--a463ffb3-1bd9-4d94-b02d-74e4f1658283",
     "description": "A simple report with an indicator and campaign",
     "id": "report--84e4d88f-44ea-4bcd-bbf3-b2c1c320bcb3",
     "labels": [
         "campaign"
     ],
-    "modified": "2015-12-21T19:59:11.000Z",
+    "modified": "2015-12-21T19:59:11Z",
     "name": "The Black Vine Cyberespionage Group",
     "object_refs": [
         "indicator--26ffb872-1dd9-446e-b6f5-d58527e5b5d2",
         "campaign--83422c77-904c-4dc1-aff5-5c38f3a2c55c",
         "relationship--f82356ae-fe6c-437c-9c24-6b64314ae68a"
     ],
-    "published": "2016-01-201T17:00:00Z",
+    "published": "2016-01-20T17:00:00Z",
     "type": "report"
 }"""
 
@@ -26,11 +30,11 @@ def test_report_example():
     report = stix2.Report(
         id="report--84e4d88f-44ea-4bcd-bbf3-b2c1c320bcb3",
         created_by_ref="identity--a463ffb3-1bd9-4d94-b02d-74e4f1658283",
-        created="2015-12-21T19:59:11.000Z",
-        modified="2015-12-21T19:59:11.000Z",
+        created="2015-12-21T19:59:11Z",
+        modified="2015-12-21T19:59:11Z",
         name="The Black Vine Cyberespionage Group",
         description="A simple report with an indicator and campaign",
-        published="2016-01-201T17:00:00Z",
+        published="2016-01-20T17:00:00Z",
         labels=["campaign"],
         object_refs=[
             "indicator--26ffb872-1dd9-446e-b6f5-d58527e5b5d2",
@@ -50,7 +54,7 @@ def test_report_example_objects_in_object_refs():
         modified="2015-12-21T19:59:11.000Z",
         name="The Black Vine Cyberespionage Group",
         description="A simple report with an indicator and campaign",
-        published="2016-01-201T17:00:00Z",
+        published="2016-01-20T17:00:00Z",
         labels=["campaign"],
         object_refs=[
             stix2.Indicator(id="indicator--26ffb872-1dd9-446e-b6f5-d58527e5b5d2", **INDICATOR_KWARGS),
@@ -71,7 +75,7 @@ def test_report_example_objects_in_object_refs_with_bad_id():
             modified="2015-12-21T19:59:11.000Z",
             name="The Black Vine Cyberespionage Group",
             description="A simple report with an indicator and campaign",
-            published="2016-01-201T17:00:00Z",
+            published="2016-01-20T17:00:00Z",
             labels=["campaign"],
             object_refs=[
                 stix2.Indicator(id="indicator--26ffb872-1dd9-446e-b6f5-d58527e5b5d2", **INDICATOR_KWARGS),
@@ -85,4 +89,41 @@ def test_report_example_objects_in_object_refs_with_bad_id():
     assert excinfo.value.reason == "must match <object-type>--<guid>."
     assert str(excinfo.value) == "Invalid value for Report 'object_refs': must match <object-type>--<guid>."
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "created": "2015-12-21T19:59:11Z",
+        "created_by_ref": "identity--a463ffb3-1bd9-4d94-b02d-74e4f1658283",
+        "description": "A simple report with an indicator and campaign",
+        "id": "report--84e4d88f-44ea-4bcd-bbf3-b2c1c320bcb3",
+        "labels": [
+            "campaign"
+        ],
+        "modified": "2015-12-21T19:59:11Z",
+        "name": "The Black Vine Cyberespionage Group",
+        "object_refs": [
+            "indicator--26ffb872-1dd9-446e-b6f5-d58527e5b5d2",
+            "campaign--83422c77-904c-4dc1-aff5-5c38f3a2c55c",
+            "relationship--f82356ae-fe6c-437c-9c24-6b64314ae68a"
+        ],
+        "published": "2016-01-20T17:00:00Z",
+        "type": "report"
+    },
+])
+def test_parse_report(data):
+    rept = stix2.parse(data)
+
+    assert rept.type == 'report'
+    assert rept.id == REPORT_ID
+    assert rept.created == dt.datetime(2015, 12, 21, 19, 59, 11, tzinfo=pytz.utc)
+    assert rept.modified == dt.datetime(2015, 12, 21, 19, 59, 11, tzinfo=pytz.utc)
+    assert rept.created_by_ref == "identity--a463ffb3-1bd9-4d94-b02d-74e4f1658283"
+    assert rept.object_refs == ["indicator--26ffb872-1dd9-446e-b6f5-d58527e5b5d2",
+                                "campaign--83422c77-904c-4dc1-aff5-5c38f3a2c55c",
+                                "relationship--f82356ae-fe6c-437c-9c24-6b64314ae68a"]
+    assert rept.description == "A simple report with an indicator and campaign"
+    assert rept.labels == ["campaign"]
+    assert rept.name == "The Black Vine Cyberespionage Group"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_sighting.py b/stix2/test/test_sighting.py
index 11f7449..9da6d4e 100644
--- a/stix2/test/test_sighting.py
+++ b/stix2/test/test_sighting.py
@@ -88,3 +88,27 @@ def test_create_sighting_from_objects_rather_than_ids(malware):  # noqa: F811
 
     assert rel.sighting_of_ref == 'malware--00000000-0000-0000-0000-000000000001'
     assert rel.id == 'sighting--00000000-0000-0000-0000-000000000002'
+
+
+@pytest.mark.parametrize("data", [
+    EXPECTED_SIGHTING,
+    {
+        "created": "2016-04-06T20:06:37Z",
+        "id": "sighting--bfbc19db-ec35-4e45-beed-f8bde2a772fb",
+        "modified": "2016-04-06T20:06:37Z",
+        "sighting_of_ref": "indicator--01234567-89ab-cdef-0123-456789abcdef",
+        "type": "sighting",
+        "where_sighted_refs": [
+            "identity--8cc7afd6-5455-4d2b-a736-e614ee631d99"
+        ]
+    },
+])
+def test_parse_sighting(data):
+    sighting = stix2.parse(data)
+
+    assert sighting.type == 'sighting'
+    assert sighting.id == SIGHTING_ID
+    assert sighting.created == dt.datetime(2016, 4, 6, 20, 6, 37, tzinfo=pytz.utc)
+    assert sighting.modified == dt.datetime(2016, 4, 6, 20, 6, 37, tzinfo=pytz.utc)
+    assert sighting.sighting_of_ref == "indicator--01234567-89ab-cdef-0123-456789abcdef"
+    assert sighting.where_sighted_refs == ["identity--8cc7afd6-5455-4d2b-a736-e614ee631d99"]
diff --git a/stix2/test/test_threat_actor.py b/stix2/test/test_threat_actor.py
index 8006ac3..5844775 100644
--- a/stix2/test/test_threat_actor.py
+++ b/stix2/test/test_threat_actor.py
@@ -1,14 +1,20 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import THREAT_ACTOR_ID
+
 EXPECTED = """{
-    "created": "2016-04-06T20:03:48.000Z",
+    "created": "2016-04-06T20:03:48Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "description": "The Evil Org threat actor group",
     "id": "threat-actor--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
     "labels": [
         "crime-syndicate"
     ],
-    "modified": "2016-04-06T20:03:48.000Z",
+    "modified": "2016-04-06T20:03:48Z",
     "name": "Evil Org",
     "type": "threat-actor"
 }"""
@@ -18,8 +24,8 @@ def test_threat_actor_example():
     threat_actor = stix2.ThreatActor(
         id="threat-actor--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T20:03:48.000Z",
-        modified="2016-04-06T20:03:48.000Z",
+        created="2016-04-06T20:03:48Z",
+        modified="2016-04-06T20:03:48Z",
         name="Evil Org",
         description="The Evil Org threat actor group",
         labels=["crime-syndicate"],
@@ -27,4 +33,32 @@ def test_threat_actor_example():
 
     assert str(threat_actor) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "created": "2016-04-06T20:03:48Z",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "description": "The Evil Org threat actor group",
+        "id": "threat-actor--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        "labels": [
+            "crime-syndicate"
+        ],
+        "modified": "2016-04-06T20:03:48Z",
+        "name": "Evil Org",
+        "type": "threat-actor"
+    },
+])
+def test_parse_threat_actor(data):
+    actor = stix2.parse(data)
+
+    assert actor.type == 'threat-actor'
+    assert actor.id == THREAT_ACTOR_ID
+    assert actor.created == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert actor.modified == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert actor.created_by_ref == "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff"
+    assert actor.description == "The Evil Org threat actor group"
+    assert actor.name == "Evil Org"
+    assert actor.labels == ["crime-syndicate"]
+
 # TODO: Add other examples
diff --git a/stix2/test/test_tool.py b/stix2/test/test_tool.py
index 201d333..3193807 100644
--- a/stix2/test/test_tool.py
+++ b/stix2/test/test_tool.py
@@ -1,13 +1,19 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import TOOL_ID
+
 EXPECTED = """{
-    "created": "2016-04-06T20:03:48.000Z",
+    "created": "2016-04-06T20:03:48Z",
     "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
     "id": "tool--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
     "labels": [
         "remote-access"
     ],
-    "modified": "2016-04-06T20:03:48.000Z",
+    "modified": "2016-04-06T20:03:48Z",
     "name": "VNC",
     "type": "tool"
 }"""
@@ -17,12 +23,38 @@ def test_tool_example():
     tool = stix2.Tool(
         id="tool--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
         created_by_ref="identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
-        created="2016-04-06T20:03:48.000Z",
-        modified="2016-04-06T20:03:48.000Z",
+        created="2016-04-06T20:03:48Z",
+        modified="2016-04-06T20:03:48Z",
         name="VNC",
         labels=["remote-access"],
     )
 
     assert str(tool) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "created": "2016-04-06T20:03:48Z",
+        "created_by_ref": "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff",
+        "id": "tool--8e2e2d2b-17d4-4cbf-938f-98ee46b3cd3f",
+        "labels": [
+            "remote-access"
+        ],
+        "modified": "2016-04-06T20:03:48Z",
+        "name": "VNC",
+        "type": "tool"
+    },
+])
+def test_parse_tool(data):
+    tool = stix2.parse(data)
+
+    assert tool.type == 'tool'
+    assert tool.id == TOOL_ID
+    assert tool.created == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert tool.modified == dt.datetime(2016, 4, 6, 20, 3, 48, tzinfo=pytz.utc)
+    assert tool.created_by_ref == "identity--f431f809-377b-45e0-aa1c-6a4751cae5ff"
+    assert tool.labels == ["remote-access"]
+    assert tool.name == "VNC"
+
 # TODO: Add other examples
diff --git a/stix2/test/test_vulnerability.py b/stix2/test/test_vulnerability.py
index 3daebd9..565f077 100644
--- a/stix2/test/test_vulnerability.py
+++ b/stix2/test/test_vulnerability.py
@@ -1,7 +1,13 @@
+import datetime as dt
+
+import pytest
+import pytz
 import stix2
 
+from .constants import VULNERABILITY_ID
+
 EXPECTED = """{
-    "created": "2016-05-12T08:17:27.000Z",
+    "created": "2016-05-12T08:17:27Z",
     "external_references": [
         {
             "external_id": "CVE-2016-1234",
@@ -9,7 +15,7 @@ EXPECTED = """{
         }
     ],
     "id": "vulnerability--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061",
-    "modified": "2016-05-12T08:17:27.000Z",
+    "modified": "2016-05-12T08:17:27Z",
     "name": "CVE-2016-1234",
     "type": "vulnerability"
 }"""
@@ -18,8 +24,8 @@ EXPECTED = """{
 def test_vulnerability_example():
     vulnerability = stix2.Vulnerability(
         id="vulnerability--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061",
-        created="2016-05-12T08:17:27.000Z",
-        modified="2016-05-12T08:17:27.000Z",
+        created="2016-05-12T08:17:27Z",
+        modified="2016-05-12T08:17:27Z",
         name="CVE-2016-1234",
         external_references=[
             stix2.ExternalReference(source_name='cve',
@@ -29,4 +35,32 @@ def test_vulnerability_example():
 
     assert str(vulnerability) == EXPECTED
 
+
+@pytest.mark.parametrize("data", [
+    EXPECTED,
+    {
+        "created": "2016-05-12T08:17:27Z",
+        "external_references": [
+            {
+                "external_id": "CVE-2016-1234",
+                "source_name": "cve"
+            }
+        ],
+        "id": "vulnerability--0c7b5b88-8ff7-4a4d-aa9d-feb398cd0061",
+        "modified": "2016-05-12T08:17:27Z",
+        "name": "CVE-2016-1234",
+        "type": "vulnerability"
+    },
+])
+def test_parse_vulnerability(data):
+    vuln = stix2.parse(data)
+
+    assert vuln.type == 'vulnerability'
+    assert vuln.id == VULNERABILITY_ID
+    assert vuln.created == dt.datetime(2016, 5, 12, 8, 17, 27, tzinfo=pytz.utc)
+    assert vuln.modified == dt.datetime(2016, 5, 12, 8, 17, 27, tzinfo=pytz.utc)
+    assert vuln.name == "CVE-2016-1234"
+    assert vuln.external_references[0].external_id == "CVE-2016-1234"
+    assert vuln.external_references[0].source_name == "cve"
+
 # TODO: Add other examples
diff --git a/stix2/utils.py b/stix2/utils.py
index 0acd5de..cdc7f54 100644
--- a/stix2/utils.py
+++ b/stix2/utils.py
@@ -1,6 +1,7 @@
 """Utility functions and classes for the stix2 library."""
 
 import datetime as dt
+import json
 
 import pytz
 
@@ -15,12 +16,35 @@ def get_timestamp():
 
 
 def format_datetime(dttm):
-    # TODO: how to handle naive datetime
+    # 1. Convert to timezone-aware
+    # 2. Convert to UTC
+    # 3. Format in ISO format
+    # 4. Add subsecond value if non-zero
+    # 5. Add "Z"
 
-    # 1. Convert to UTC
-    # 2. Format in ISO format
-    # 3. Strip off "+00:00"
-    # 4. Add "Z"
+    try:
+        zoned = dttm.astimezone(pytz.utc)
+    except ValueError:
+        # dttm is timezone-naive; assume UTC
+        pytz.utc.localize(dttm)
+    ts = zoned.strftime("%Y-%m-%dT%H:%M:%S")
+    if zoned.microsecond > 0:
+        ms = zoned.strftime("%f")
+        ts = ts + '.' + ms.rstrip("0")
+    return ts + "Z"
 
-    # TODO: how to handle timestamps with subsecond 0's
-    return dttm.astimezone(pytz.utc).isoformat()[:-6] + "Z"
+
+def get_dict(data):
+    """Return data as a dictionary.
+    Input can be a dictionary, string, or file-like object.
+    """
+
+    if type(data) is dict:
+        obj = data
+    else:
+        try:
+            obj = json.loads(data)
+        except TypeError:
+            obj = json.load(data)
+
+    return obj
diff --git a/tox.ini b/tox.ini
index fd580f9..80213d7 100644
--- a/tox.ini
+++ b/tox.ini
@@ -8,10 +8,11 @@ commands = pytest
 [testenv:pycodestyle]
 deps =
   flake8
+  flake8-import-order
   pycodestyle
 commands =
   pycodestyle ./stix2
-  flake8 --max-line-length=160
+  flake8 --max-line-length=160 --import-order-style='google'
 
 [pycodestyle]
 ignore=