diff --git a/.travis.yml b/.travis.yml
index af97f31..ca3c0c8 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -6,7 +6,7 @@ python:
   - pypy
   - pypy3
 script:
-  - coverage run -m zope.testrunner
+  - coverage run -m zope.testrunner --test-path=src
 after_success:
   - coveralls
 notifications:
diff --git a/CHANGES.rst b/CHANGES.rst
index 0958f3e..f88f7ad 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -8,3 +8,5 @@
 
 - First PyPI release.
 - Add support for Python 3.
+- Drop support for externalizing to plists. See
+  https://github.com/NextThought/nti.externalization/issues/21
diff --git a/docs/conf.py b/docs/conf.py
index 746256d..9a60e50 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -169,6 +169,8 @@
     'https://docs.python.org/': None,
     #'https://ntiwref.readthedocs.io/en/latest': None,
     'https://persistent.readthedocs.io/en/latest': None,
+    'https://zopecomponent.readthedocs.io/en/latest': None,
+    'https://zodb.readthedocs.io/en/latest': None,
 }
 
 extlinks = {
diff --git a/src/nti/externalization/configure.zcml b/src/nti/externalization/configure.zcml
index 23ff82b..589d95c 100644
--- a/src/nti/externalization/configure.zcml
+++ b/src/nti/externalization/configure.zcml
@@ -35,7 +35,6 @@
 
 	<utility factory=".representation.JsonRepresenter" />
 	<utility factory=".representation.YamlRepresenter" />
-	<utility factory=".representation.PlistRepresenter" />
 
 	<!-- Offer to adapt strings to dates -->
 	<!-- TODO: This is a bit ad-hoc. Surely there's a more formal set
diff --git a/src/nti/externalization/externalization.py b/src/nti/externalization/externalization.py
index 15b428d..1fe93de 100644
--- a/src/nti/externalization/externalization.py
+++ b/src/nti/externalization/externalization.py
@@ -264,12 +264,7 @@ def _to_external_object_state(obj, state, top_level=False, decorate=True,
                 result.append(ext_obj)
             result = state.registry.getAdapter(result,
                                                ILocatedExternalSequence)
-        # PList doesn't support None values, JSON does. The closest
-        # coersion I can think of is False.
-        elif obj is None:
-            if state.coerceNone:
-                result = False
-        else:
+        elif obj is not None:
             # Otherwise, we probably won't be able to JSON-ify it.
             # TODO: Should this live here, or at a higher level where the ultimate
             # external target/use-case is known?
@@ -307,7 +302,6 @@ def _to_external_object_state(obj, state, top_level=False, decorate=True,
 
 
 def toExternalObject(obj,
-                     coerceNone=False,
                      name=_NotGiven,
                      registry=component,
                      catch_components=(),
@@ -677,8 +671,9 @@ def _clean(m):
     "nti.externalization.persistence",
     "NoPickle")
 
-EXT_FORMAT_JSON = 'json'      #: Constant requesting JSON format data
-EXT_FORMAT_PLIST = 'plist'  #: Constant requesting PList (XML) format data
+#: Constant requesting JSON format data
+EXT_FORMAT_JSON = 'json'
+
 
 zope.deferredimport.deprecatedFrom(
     "Import from .representation",
diff --git a/src/nti/externalization/interfaces.py b/src/nti/externalization/interfaces.py
index bb55baf..a40ec55 100644
--- a/src/nti/externalization/interfaces.py
+++ b/src/nti/externalization/interfaces.py
@@ -3,24 +3,29 @@
 """
 Externalization Interfaces
 
-.. $Id$
 """
 
 from __future__ import print_function, absolute_import, division
 __docformat__ = "restructuredtext en"
 
-logger = __import__('logging').getLogger(__name__)
-
 from zope import interface
 
 from zope.component.interfaces import IFactory
 
 from zope.interface.common.mapping import IFullMapping
-
 from zope.interface.common.sequence import ISequence
 
 from zope.location import ILocation
 
+from zope.interface.interfaces import ObjectEvent
+from zope.interface.interfaces import IObjectEvent
+
+from zope.lifecycleevent import ObjectModifiedEvent
+from zope.lifecycleevent import IObjectModifiedEvent
+
+
+# pylint:disable=inherit-non-class,no-method-argument,no-self-argument
+
 
 class StandardExternalFields(object):
     """
@@ -92,7 +97,7 @@ class INonExternalizableReplacer(interface.Interface):
     some object cannot be externalized.
     """
 
-    def __call__(obj):
+    def __call__(obj): # pylint:disable=signature-differs
         """
         :return: An externalized object to replace the given object. Possibly the
                 given object itself if some higher level will handle it.
@@ -126,10 +131,11 @@ def decorateExternalObject(origial, external):
         though this is not guaranteed).
 
         :param original: The object that is being externalized.
-                Passed to facilitate using non-classes as decorators.
+            Passed to facilitate using non-classes as decorators.
         :param external: The externalization of that object, produced
-                by an implementation of :class:`~nti.externalization.interfaces.IInternalObjectExternalizer` or
-                default rules.
+            by an implementation of
+            :class:`~nti.externalization.interfaces.IInternalObjectExternalizer`
+            or default rules.
         :return: Undefined.
         """
 
@@ -153,11 +159,11 @@ def decorateExternalMapping(original, external):
         Decorate the externalized object mapping.
 
         :param original: The object that is being externalized. Passed
-                to facilitate using non-classes as decorators.
+            to facilitate using non-classes as decorators.
         :param external: The externalization of that object, an
-                :class:`~nti.externalization.interfaces.ILocatedExternalMapping`,
-                produced by an implementation of
-                :class:`~nti.externalization.interfaces.IInternalObjectExternalizer` or default rules.
+            :class:`~nti.externalization.interfaces.ILocatedExternalMapping`,
+            produced by an implementation of
+            :class:`~nti.externalization.interfaces.IInternalObjectExternalizer` or default rules.
         :return: Undefined.
         """
 
@@ -186,8 +192,10 @@ class ILocatedExternalSequence(IExternalizedObject, ILocation, ISequence):
 @interface.implementer(ILocatedExternalMapping)
 class LocatedExternalDict(dict):
     """
-    A dictionary that implements :class:`~nti.externalization.interfaces.ILocatedExternalMapping`. Returned
-    by :func:`~nti.externalization.externalization.to_standard_external_dictionary`.
+    A dictionary that implements
+    :class:`~nti.externalization.interfaces.ILocatedExternalMapping`.
+    Returned by
+    :func:`~nti.externalization.externalization.to_standard_external_dictionary`.
 
     This class is not :class:`.IContentTypeAware`, and it indicates so explicitly by declaring a
     `mime_type` value of None.
@@ -202,8 +210,10 @@ class LocatedExternalDict(dict):
 @interface.implementer(ILocatedExternalSequence)
 class LocatedExternalList(list):
     """
-    A list that implements :class:`~nti.externalization.interfaces.ILocatedExternalSequence`. Returned
-    by :func:`~nti.externalization.externalization.to_external_object`.
+    A list that implements
+    :class:`~nti.externalization.interfaces.ILocatedExternalSequence`.
+    Returned by
+    :func:`~nti.externalization.externalization.to_external_object`.
 
     This class is not :class:`.IContentTypeAware`, and it indicates so explicitly by declaring a
     `mimeType` value of None.
@@ -260,9 +270,6 @@ class IExternalObjectIO(IExternalObjectRepresenter,
 #: Constant requesting JSON format data
 EXT_REPR_JSON = u'json'
 
-#: Constant requesting PList (XML) format data
-EXT_REPR_PLIST = u'plist'
-
 #: Constant requesting YAML format data
 EXT_REPR_YAML = u'yaml'
 
@@ -290,8 +297,9 @@ class IExternalizedObjectFactoryFinder(interface.Interface):
 
     def find_factory(externalized_object):
         """
-        Given an externalized object, return a :class:`zope.component.interfaces.IFactory` to create the proper
-        internal types.
+        Given an externalized object, return a
+        :class:`zope.component.interfaces.IFactory` to create the
+        proper internal types.
 
         :return: An :class:`zope.component.interfaces.IFactory`, or :const:`None`.
         """
@@ -347,14 +355,6 @@ class IInternalObjectIO(IInternalObjectExternalizer, IInternalObjectUpdater):
     in external forms.
     """
 
-
-from zope.interface.interfaces import ObjectEvent
-from zope.interface.interfaces import IObjectEvent
-
-from zope.lifecycleevent import ObjectModifiedEvent
-from zope.lifecycleevent import IObjectModifiedEvent
-
-
 class IObjectWillUpdateFromExternalEvent(IObjectEvent):
     """
     An object will be updated from an external value.
diff --git a/src/nti/externalization/internalization.py b/src/nti/externalization/internalization.py
index feebcae..582f20c 100644
--- a/src/nti/externalization/internalization.py
+++ b/src/nti/externalization/internalization.py
@@ -304,8 +304,7 @@ def update_from_external_object(containedObject, externalObject,
             ``v`` is the newly-updated value, and ``x`` is the external object used to update ``v``.
     :param callable pre_hook: If given, called with the before update_from_external_object is
             called for every nested object. Signature ``f(k,x)`` where ``k`` is either the key name,
-             or None in the case of a sequence and ``x`` is the external object
-
+            or None in the case of a sequence and ``x`` is the external object
     :return: `containedObject` after updates from `externalObject`
     """
 
diff --git a/src/nti/externalization/representation.py b/src/nti/externalization/representation.py
index 7646e91..05511a9 100644
--- a/src/nti/externalization/representation.py
+++ b/src/nti/externalization/representation.py
@@ -3,17 +3,11 @@
 """
 External representation support.
 
-.. $Id$
 """
 
 from __future__ import print_function, absolute_import, division
 __docformat__ = "restructuredtext en"
 
-import collections
-import plistlib
-
-import six
-from six import iteritems
 
 from zope import component
 from zope import interface
@@ -22,7 +16,6 @@
 
 from nti.externalization.interfaces import EXT_REPR_JSON
 from nti.externalization.interfaces import EXT_REPR_YAML
-from nti.externalization.interfaces import EXT_REPR_PLIST
 
 from nti.externalization.interfaces import IExternalObjectIO
 from nti.externalization.interfaces import IExternalObjectRepresenter
@@ -36,9 +29,11 @@
 def to_external_representation(obj, ext_format=EXT_REPR_JSON,
                                name=_NotGiven, registry=component):
     """
-    Transforms (and returns) the `obj` into its external (string) representation.
+    Transforms (and returns) the `obj` into its external (string)
+    representation.
 
-    :param ext_format: One of :const:`EXT_FORMAT_JSON` or :const:`EXT_FORMAT_PLIST`.
+    :param ext_format: One of :const:`nti.externalization.interfaces.EXT_REPR_JSON` or
+        :const:`nti.externalization.interfaces.EXT_REPR_YAML`.
     """
     # It would seem nice to be able to do this in one step during
     # the externalization process itself, but we would wind up traversing
@@ -57,39 +52,6 @@ def to_json_representation(obj):
     return to_external_representation(obj, EXT_REPR_JSON)
 
 
-# Plist
-
-
-
-# The API changed in Python 3.4
-_plist_dump = getattr(plistlib, 'dump', None) or plistlib.writePlist
-_plist_dumps = getattr(plistlib, 'dumps', None) or plistlib.writePlistToString
-
-
-@interface.named(EXT_REPR_PLIST)
-@interface.implementer(IExternalObjectRepresenter)
-class PlistRepresenter(object):
-
-    def stripNoneFromExternal(self, obj):
-        """
-        Given an already externalized object, strips ``None`` values.
-        """
-        if isinstance(obj, (list, tuple)):
-            obj = [self.stripNoneFromExternal(x) for x in obj if x is not None]
-        elif isinstance(obj, collections.Mapping):
-            obj = {k: self.stripNoneFromExternal(v)
-                   for k, v in iteritems(obj)
-                   if v is not None and k is not None}
-        return obj
-
-    def dump(self, obj, fp=None):
-        ext = self.stripNoneFromExternal(obj)
-        if fp is not None:
-            _plist_dump(ext, fp)
-        else:
-            return _plist_dumps(ext)
-
-
 # JSON
 
 
@@ -143,7 +105,7 @@ def load(self, stream):
         # Depending on whether the simplejson C speedups are active, we can still
         # get back a non-unicode string if the object was a naked string. (If the python
         # version is used, it returns unicode; the C version returns str.)
-        if isinstance(value, six.binary_type):
+        if isinstance(value, bytes):
             # we know it's simple ascii or it would have produced unicode
             value = to_unicode(value)
         return value
@@ -199,10 +161,7 @@ def load(self, stream):
 from ZODB.POSException import ConnectionStateError
 
 
-def make_repr(default=None):
-    if default is None:
-        def default(self):
-            return "%s().__dict__.update( %s )" % (self.__class__.__name__, self.__dict__)
+def make_repr(default=lambda self: "%s().__dict__.update( %s )" % (self.__class__.__name__, self.__dict__)):
 
     def __repr__(self):
         try:
diff --git a/src/nti/externalization/tests/test_externalization.py b/src/nti/externalization/tests/test_externalization.py
index e1143ab..e579b4f 100644
--- a/src/nti/externalization/tests/test_externalization.py
+++ b/src/nti/externalization/tests/test_externalization.py
@@ -25,7 +25,7 @@
 
 import sys
 import json
-import plistlib
+
 import unittest
 
 try:
@@ -43,8 +43,6 @@
 from nti.externalization.datastructures import ExternalizableInstanceDict
 from nti.externalization.datastructures import ExternalizableDictionaryMixin
 
-from nti.externalization.externalization import EXT_FORMAT_JSON
-from nti.externalization.externalization import EXT_FORMAT_PLIST
 
 from nti.externalization.externalization import _manager
 from nti.externalization.externalization import _DevmodeNonExternalizableObjectReplacer
@@ -57,6 +55,7 @@
 from nti.externalization.externalization import to_standard_external_dictionary
 
 from nti.externalization.interfaces import EXT_REPR_YAML
+from nti.externalization.interfaces import EXT_REPR_JSON
 from nti.externalization.interfaces import LocatedExternalList
 from nti.externalization.interfaces import LocatedExternalDict
 
@@ -136,13 +135,8 @@ def test_hookable(self):
     def test_to_external_representation_none_handling(self):
         d = {'a': 1, 'None': None}
         # JSON keeps None
-        assert_that(json.loads(to_external_representation(d, EXT_FORMAT_JSON)),
+        assert_that(json.loads(to_external_representation(d, EXT_REPR_JSON)),
                     is_(d))
-        # PList strips it
-        # The api changed in Python 3.4
-        read_plist = getattr(plistlib, 'loads', getattr(plistlib, 'readPlistFromString', None))
-        assert_that(read_plist(to_external_representation(d, EXT_FORMAT_PLIST)),
-                    is_({'a': 1}))
 
     def test_to_external_representation_yaml(self):
         l = LocatedExternalList()