diff --git a/stix2/base.py b/stix2/base.py
index b26f044..d7c7553 100644
--- a/stix2/base.py
+++ b/stix2/base.py
@@ -153,15 +153,7 @@ class _STIXBase(collections.Mapping):
         super(_STIXBase, self).__setattr__(name, value)
 
     def __str__(self):
-        properties = self.object_properties()
-
-        def sort_by(element):
-            return find_property_index(self, properties, element)
-
-        # separators kwarg -> don't include spaces after commas.
-        return json.dumps(self, indent=4, cls=STIXJSONEncoder,
-                          item_sort_key=sort_by,
-                          separators=(",", ": "))
+        return self.serialize(pretty=True)
 
     def __repr__(self):
         props = [(k, self[k]) for k in self.object_properties() if self.get(k)]
@@ -185,6 +177,38 @@ class _STIXBase(collections.Mapping):
     def revoke(self):
         return _revoke(self)
 
+    def serialize(self, pretty=False, **kwargs):
+        """
+        Serialize a STIX object.
+
+        Args:
+            pretty (bool): If True, output properties following the STIX specs
+                formatting. This includes indentation. Refer to notes for more
+                details.
+            **kwargs: The arguments for a json.dumps() call.
+
+        Returns:
+            dict: The serialized JSON object.
+
+        Note:
+            The argument ``pretty=True`` will output the STIX object following
+            spec order. Using this argument greatly impacts object serialization
+            performance. If your use case is centered across machine-to-machine
+            operation it is recommended to set ``pretty=False``.
+
+            When ``pretty=True`` the following key-value pairs will be added or
+            overridden: indent=4, separators=(",", ": "), item_sort_key=sort_by.
+        """
+        if pretty:
+            properties = self.object_properties()
+
+            def sort_by(element):
+                return find_property_index(self, properties, element)
+
+            kwargs.update({'indent': 4, 'separators': (",", ": "), 'item_sort_key': sort_by})
+
+        return json.dumps(self, cls=STIXJSONEncoder, **kwargs)
+
 
 class _Observable(_STIXBase):
 
diff --git a/stix2/test/test_bundle.py b/stix2/test/test_bundle.py
index b1cffd0..262b050 100644
--- a/stix2/test/test_bundle.py
+++ b/stix2/test/test_bundle.py
@@ -1,8 +1,9 @@
+import json
+
 import pytest
 
 import stix2
 
-
 EXPECTED_BUNDLE = """{
     "type": "bundle",
     "id": "bundle--00000000-0000-0000-0000-000000000004",
@@ -41,6 +42,44 @@ EXPECTED_BUNDLE = """{
     ]
 }"""
 
+EXPECTED_BUNDLE_DICT = {
+    "type": "bundle",
+    "id": "bundle--00000000-0000-0000-0000-000000000004",
+    "spec_version": "2.0",
+    "objects": [
+        {
+            "type": "indicator",
+            "id": "indicator--00000000-0000-0000-0000-000000000001",
+            "created": "2017-01-01T12:34:56.000Z",
+            "modified": "2017-01-01T12:34:56.000Z",
+            "pattern": "[file:hashes.MD5 = 'd41d8cd98f00b204e9800998ecf8427e']",
+            "valid_from": "2017-01-01T12:34:56Z",
+            "labels": [
+                "malicious-activity"
+            ]
+        },
+        {
+            "type": "malware",
+            "id": "malware--00000000-0000-0000-0000-000000000002",
+            "created": "2017-01-01T12:34:56.000Z",
+            "modified": "2017-01-01T12:34:56.000Z",
+            "name": "Cryptolocker",
+            "labels": [
+                "ransomware"
+            ]
+        },
+        {
+            "type": "relationship",
+            "id": "relationship--00000000-0000-0000-0000-000000000003",
+            "created": "2017-01-01T12:34:56.000Z",
+            "modified": "2017-01-01T12:34:56.000Z",
+            "relationship_type": "indicates",
+            "source_ref": "indicator--01234567-89ab-cdef-0123-456789abcdef",
+            "target_ref": "malware--fedcba98-7654-3210-fedc-ba9876543210"
+        }
+    ]
+}
+
 
 def test_empty_bundle():
     bundle = stix2.Bundle()
@@ -82,10 +121,18 @@ def test_bundle_with_wrong_spec_version():
     assert str(excinfo.value) == "Invalid value for Bundle 'spec_version': must equal '2.0'."
 
 
-def test_create_bundle(indicator, malware, relationship):
+def test_create_bundle1(indicator, malware, relationship):
     bundle = stix2.Bundle(objects=[indicator, malware, relationship])
 
     assert str(bundle) == EXPECTED_BUNDLE
+    assert bundle.serialize(pretty=True) == EXPECTED_BUNDLE
+
+
+def test_create_bundle2(indicator, malware, relationship):
+    bundle = stix2.Bundle(objects=[indicator, malware, relationship])
+
+    print(repr(bundle))
+    assert json.loads(bundle.serialize()) == EXPECTED_BUNDLE_DICT
 
 
 def test_create_bundle_with_positional_args(indicator, malware, relationship):