diff --git a/.gitignore b/.gitignore
index b805b4c64..0a831cdbf 100644
--- a/.gitignore
+++ b/.gitignore
@@ -11,7 +11,7 @@ __pycache__/
 # Distribution / packaging
 bin/
 .Python
-env/
+env*/
 build/
 develop-eggs/
 dist/
@@ -27,8 +27,10 @@ var/
 *.egg
 MANIFEST
 .eggs/
+.env*/
 .pyenv/
-.venv/
+venv*/
+.venv*/
 
 # PyInstaller
 #  Usually these files are written by a python script from a template
diff --git a/.pylintrc b/.pylintrc
index f5888bd5e..20209a128 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -201,7 +201,7 @@ defining-attr-methods=__init__,__new__,setUp
 valid-classmethod-first-arg=cls
 
 # List of valid names for the first argument in a metaclass class method.
-valid-metaclass-classmethod-first-arg=mcs
+valid-metaclass-classmethod-first-arg=mcs,metacls
 
 
 [DESIGN]
@@ -226,7 +226,7 @@ max-branches=12
 max-statements=50
 
 # Maximum number of parents for a class (see R0901).
-max-parents=7
+max-parents=14
 
 # Maximum number of attributes for a class (see R0902).
 max-attributes=15
diff --git a/.travis.yml b/.travis.yml
index c75c86092..31239bb09 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,8 +20,10 @@ matrix:
       env: TOX_ENV=py34
     - python: 3.5
       env: TOX_ENV=py35
+    - python: 3.6
+      env: TOX_ENV=py36
     - python: pypy
-      env: TOX_ENV=pypy PYPY_VERSION='4.0.0'
+      env: TOX_ENV=pypy PYPY_VERSION='2.7-5.8.0'
     - python: 2.7
       env: TOX_ENV=pep8
     - python: 2.7
diff --git a/.travis/install.sh b/.travis/install.sh
index e4ea39234..92ba34509 100755
--- a/.travis/install.sh
+++ b/.travis/install.sh
@@ -41,9 +41,13 @@ if [[ "$(uname -s)" == 'Darwin' ]]; then
             pyenv install 3.5.0
             pyenv global 3.5.0
             ;;
+        py36)
+            pyenv install 3.6.0
+            pyenv global 3.6.0
+            ;;
         pypy)
-            pyenv install "pypy-${PYPY_VERSION}"
-            pyenv global "pypy-${PYPY_VERSION}"
+            pyenv install "pypy${PYPY_VERSION}"
+            pyenv global "pypy${PYPY_VERSION}"
             ;;
     esac
     pyenv rehash
@@ -55,8 +59,8 @@ else
         export PYENV_ROOT="$PWD/.pyenv"
         export PATH="$PYENV_ROOT/bin:$PATH"
         eval "$(pyenv init -)"
-        pyenv install "pypy-${PYPY_VERSION}"
-        pyenv global "pypy-${PYPY_VERSION}"
+        pyenv install "pypy${PYPY_VERSION}"
+        pyenv global "pypy${PYPY_VERSION}"
     fi
     pip install -U virtualenv
 fi
diff --git a/.travis/run.sh b/.travis/run.sh
index 7de433046..66b145c7c 100755
--- a/.travis/run.sh
+++ b/.travis/run.sh
@@ -14,7 +14,7 @@ else
         export PYENV_ROOT="$PWD/.pyenv"
         export PATH="$PYENV_ROOT/bin:$PATH"
         eval "$(pyenv init -)"
-        pyenv global "pypy-${PYPY_VERSION}"
+        pyenv global "pypy${PYPY_VERSION}"
     fi
 fi
 source $PWD/.venv/bin/activate
diff --git a/HISTORY.rst b/HISTORY.rst
index 25def3f5b..eeedd9b5c 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -6,7 +6,18 @@ Release History
 Upcoming
 ++++++++
 
-1.5.3
+1.5.4
+++++++++++++++++++
+
+- Bugfix so that the return value of ``JWTAuth.refresh()`` correctly matches
+  that of the auth interface (by returning a tuple of
+  ((access token), (refresh token or None)), instead of just the access token).
+  In particular, this fixes an exception in ``BoxSession`` that always occurred
+  when it tried to refresh any ``JWTAuth`` object.
+- Fixed an exception that was being raised from ``ExtendableEnumMeta.__dir__()``.
+- CPython 3.6 support.
+
+1.5.3 (2016-05-26)
 ++++++++++++++++++
 
 - Bugfix so that ``JWTAuth`` opens the PEM private key file in ``'rb'`` mode.
diff --git a/README.rst b/README.rst
index fa551e1e7..ad1fd368f 100644
--- a/README.rst
+++ b/README.rst
@@ -28,8 +28,34 @@ Installing
 
 .. code-block:: console
 
-    pip install boxsdk
-
+    pip install "boxsdk>=1.5,<2.0"
+
+Important Versioning Note
+-------------------------
+
+The production version of the ``boxsdk`` package is the 1.5.x release track.
+The code can be found on Github at
+<https://github.com/box/box-python-sdk/tree/1.5>. This is what will be
+installed with ``pip install boxsdk``.
+
+The development version of the ``boxsdk`` package is the 2.0.0 release track,
+currently in an alpha release.  The code can be found on Github at
+<https://github.com/box/box-python-sdk/tree/master>. This isn't installed by
+``pip`` by default, but can be installed if specifying a specific version. For
+example, ``pip install boxsdk==2.0.0a5``. We welcome early testing and feedback
+on these alpha releases. Note that while we're still in alpha, version 2.0.0 is
+subject to change, and there might be breaking changes between alpha releases
+(e.g. between 2.0.0a2 and 2.0.0a3).
+
+The 1.5.x release track will receive bugfix support at least until the final
+release of 2.0.0.
+
+We always recommend pinning to a specific version (e.g. by adding
+``boxsdk==1.5.3`` in your ``requirements.txt`` file), so that you don't risk
+accidentally upgrading to a new version and breaking your application. This is
+particularly important with the upcoming 2.0.0 release. There will be some
+breaking changes in version 2.0.0, which might break your application if you
+upgrade without adapting your code first.
 
 Authorization
 -------------
@@ -418,8 +444,8 @@ Run all tests using -
 
 The tox tests include code style checks via pep8 and pylint.
 
-The tox tests are configured to run on Python 2.6, 2.7, 3.3, 3.4, 3.5, and
-PyPy (our CI is configured to run PyPy tests on PyPy 4.0).
+The tox tests are configured to run on Python 2.6, 2.7, 3.3, 3.4, 3.5, 3.6, and
+PyPy2.7 (our CI is configured to run PyPy2.7 tests on PyPy2.7 5.8.0).
 
 
 Support
diff --git a/boxsdk/auth/jwt_auth.py b/boxsdk/auth/jwt_auth.py
index 266fff254..3d95cca64 100644
--- a/boxsdk/auth/jwt_auth.py
+++ b/boxsdk/auth/jwt_auth.py
@@ -193,6 +193,7 @@ def _refresh(self, access_token):
         """
         # pylint:disable=unused-argument
         if self._user_id is None:
-            return self.authenticate_instance()
+            new_access_token = self.authenticate_instance()
         else:
-            return self._auth_with_jwt(self._user_id, 'user')
+            new_access_token = self._auth_with_jwt(self._user_id, 'user')
+        return new_access_token, None
diff --git a/boxsdk/auth/oauth2.py b/boxsdk/auth/oauth2.py
index 6b0e9d587..8112a9888 100644
--- a/boxsdk/auth/oauth2.py
+++ b/boxsdk/auth/oauth2.py
@@ -203,14 +203,13 @@ def refresh(self, access_token_to_refresh):
             # The lock here is for handling that case that multiple requests fail, due to access token expired, at the
             # same time to avoid multiple session renewals.
             if (access_token is None) or (access_token_to_refresh == access_token):
-                # If the active access token is the same as the token needs to
+                # If the active access token is the same as the token that needs to
                 # be refreshed, or if we don't currently have any active access
                 # token, we make the request to refresh the token.
-                return self._refresh(access_token_to_refresh)
-            else:
-                # If the active access token (self._access_token) is not the same as the token needs to be refreshed,
-                # it means the expired token has already been refreshed. Simply return the current active tokens.
-                return access_token, refresh_token
+                access_token, refresh_token = self._refresh(access_token_to_refresh)
+            # Else, if the active access token (self._access_token) is not the same as the token needs to be refreshed,
+            # it means the expired token has already been refreshed. Simply return the current active tokens.
+            return access_token, refresh_token
 
     @staticmethod
     def _get_state_csrf_token():
diff --git a/boxsdk/object/events.py b/boxsdk/object/events.py
index dbb321f76..39c058f52 100644
--- a/boxsdk/object/events.py
+++ b/boxsdk/object/events.py
@@ -1,14 +1,13 @@
 # coding: utf-8
 
-from __future__ import unicode_literals
-
+from __future__ import unicode_literals, absolute_import
 from requests.exceptions import Timeout
-from six import with_metaclass
 
-from boxsdk.object.base_endpoint import BaseEndpoint
-from boxsdk.util.enum import ExtendableEnumMeta
-from boxsdk.util.lru_cache import LRUCache
-from boxsdk.util.text_enum import TextEnum
+from .base_endpoint import BaseEndpoint
+from ..util.compat import with_metaclass
+from ..util.enum import ExtendableEnumMeta
+from ..util.lru_cache import LRUCache
+from ..util.text_enum import TextEnum
 
 
 # pylint:disable=too-many-ancestors
@@ -55,6 +54,7 @@ class Events(BaseEndpoint):
 
     def get_url(self, *args):
         """Base class override."""
+        # pylint:disable=arguments-differ
         return super(Events, self).get_url('events', *args)
 
     def get_events(self, limit=100, stream_position=0, stream_type=UserEventsStreamType.ALL):
diff --git a/boxsdk/util/compat.py b/boxsdk/util/compat.py
index 33fbea5c2..9f5897a47 100644
--- a/boxsdk/util/compat.py
+++ b/boxsdk/util/compat.py
@@ -1,10 +1,12 @@
 # coding: utf-8
 
-from __future__ import division, unicode_literals
-
+from __future__ import absolute_import, division, unicode_literals
 
 from datetime import timedelta
 
+import six
+
+
 if not hasattr(timedelta, 'total_seconds'):
     def total_seconds(delta):
         """
@@ -15,3 +17,61 @@ def total_seconds(delta):
 else:
     def total_seconds(delta):
         return delta.total_seconds()
+
+
+def with_metaclass(meta, *bases, **with_metaclass_kwargs):
+    """Extends the behavior of six.with_metaclass.
+
+    The normal usage (expanded to include temporaries, to make the illustration
+    easier) is:
+
+    .. code-block:: python
+
+        temporary_class = six.with_metaclass(meta, *bases)
+        temporary_metaclass = type(temporary_class)
+
+        class Subclass(temporary_class):
+            ...
+
+        SubclassMeta = type(Subclass)
+
+    In this example:
+
+    - ``temporary_class`` is a class with ``(object,)`` as its bases.
+    - ``temporary_metaclass`` is a metaclass with ``(meta,)`` as its bases.
+    - ``Subclass`` is a class with ``bases`` as its bases.
+    - ``SubclassMeta`` is ``meta``.
+
+    ``six.with_metaclass()`` is defined in such a way that it can make sure
+    that ``Subclass`` has the correct metaclass and bases, while only using
+    syntax which is common to both Python 2 and Python 3.
+    ``temporary_metaclass()`` returns an instance of ``meta``, rather than an
+    instance of itself / a subclass of ``temporary_class``, which is how
+    ``SubclassMeta`` ends up being ``meta``, and how the temporaries don't
+    appear anywhere in the final subclass.
+
+    There are two problems with the current (as of six==1.10.0) implementation
+    of ``six.with_metaclass()``, which this function solves.
+
+    ``six.with_metaclass()`` does not define ``__prepare__()`` on the temporary
+    metaclass. This means that ``meta.__prepare__()`` gets called directly,
+    with bases set to ``(object,)``. If it needed to actually receive
+    ``bases``, then errors might occur. For example, this was a problem when
+    used with ``enum.EnumMeta`` in Python 3.6. Here we make sure that
+    ``__prepare__()`` is defined on the temporary metaclass, and pass ``bases``
+    to ``meta.__prepare__()``.
+
+    Since ``temporary_class`` doesn't have the correct bases, in theory this
+    could cause other problems, besides the previous one, in certain edge
+    cases. To make sure that doesn't become a problem, we make sure that
+    ``temporary_class`` has ``bases`` as its bases, just like the final class.
+    """
+    temporary_class = six.with_metaclass(meta, *bases, **with_metaclass_kwargs)
+    temporary_metaclass = type(temporary_class)
+
+    class TemporaryMetaSubclass(temporary_metaclass):
+        @classmethod
+        def __prepare__(cls, name, this_bases, **kwds):  # pylint:disable=unused-argument
+            return meta.__prepare__(name, bases, **kwds)
+
+    return type.__new__(TemporaryMetaSubclass, str('temporary_class'), bases, {})
diff --git a/boxsdk/util/enum.py b/boxsdk/util/enum.py
index 109103393..1988d9663 100644
--- a/boxsdk/util/enum.py
+++ b/boxsdk/util/enum.py
@@ -1,4 +1,5 @@
 # coding: utf-8
+# pylint:disable=no-value-for-parameter
 
 from __future__ import absolute_import, unicode_literals
 
@@ -20,7 +21,9 @@ class ExtendableEnumMeta(EnumMeta):
 
     This allows you to define hierarchies such as this:
 
-        class EnumBase(six.with_metaclass(ExtendableEnumMeta, Enum)): pass
+        from box.util.compat import with_metaclass
+
+        class EnumBase(with_metaclass(ExtendableEnumMeta, Enum)): pass
 
         class Enum1(EnumBase):
             A = 'A'
@@ -99,7 +102,7 @@ def in_(subclass):
         return any(map(in_, cls.__subclasses__()))
 
     def __dir__(cls):
-        return list(set(super(ExtendableEnumMeta, cls).__dir__()).union(set(map(dir, cls.__subclasses__()))))
+        return list(set(super(ExtendableEnumMeta, cls).__dir__()).union(*map(dir, cls.__subclasses__())))
 
     def __getitem__(cls, name):
         try:
@@ -129,7 +132,7 @@ def __getattr__(cls, name):
                 # and __getitem__ have the same behavior. And __getitem__ has
                 # the advantage of never grabbing anything other than enum
                 # members.
-                return cls[name]
+                return cls[name]  # pylint:disable=unsubscriptable-object
             except KeyError:
                 pass
             # This needs to be `reraise()`, and not just `raise`. Otherwise,
diff --git a/boxsdk/version.py b/boxsdk/version.py
index e4cd37ccc..9b4b21f71 100644
--- a/boxsdk/version.py
+++ b/boxsdk/version.py
@@ -3,4 +3,4 @@
 from __future__ import unicode_literals, absolute_import
 
 
-__version__ = '1.5.3'
+__version__ = '1.5.4'
diff --git a/requirements-dev.txt b/requirements-dev.txt
index 66fa4cd6a..2f495a244 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -3,10 +3,15 @@ bottle
 jsonpatch
 mock>=2.0.0
 pep8
-pylint
+
+# Pin to an old version so that new errors don't start appearing on the
+# bugfix-only 1.5 branch. Don't propagate this pinned version to the master
+# branch.
+pylint==1.5.5
+
 pytest>=2.8.3
 pytest-cov
 pytest-xdist
-sphinx
+sphinx>=1.5,<1.6
 sqlalchemy
-tox
\ No newline at end of file
+tox
diff --git a/requirements.txt b/requirements.txt
index 0e0ef6918..5e33286f8 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -4,4 +4,4 @@ pyjwt>=1.3.0
 requests>=2.4.3
 requests-toolbelt>=0.4.0
 six >= 1.4.0
--e .
+-e .[all]
diff --git a/setup.cfg b/setup.cfg
index 4503092ce..2195a80c2 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -6,3 +6,6 @@ universal=1
 
 [metadata]
 license_file=LICENSE
+
+[isort]
+known_first_party=test
diff --git a/setup.py b/setup.py
index ef4fb24ea..64ced4d99 100644
--- a/setup.py
+++ b/setup.py
@@ -22,6 +22,7 @@
     'Programming Language :: Python :: 3.3',
     'Programming Language :: Python :: 3.4',
     'Programming Language :: Python :: 3.5',
+    'Programming Language :: Python :: 3.6',
     'Programming Language :: Python :: Implementation :: CPython',
     'Programming Language :: Python :: Implementation :: PyPy',
     'Operating System :: OS Independent',
diff --git a/test/functional/mock_box/util/chaos_utils.py b/test/functional/mock_box/util/chaos_utils.py
index c669587fe..e6df75973 100644
--- a/test/functional/mock_box/util/chaos_utils.py
+++ b/test/functional/mock_box/util/chaos_utils.py
@@ -1,15 +1,35 @@
 # coding: utf-8
 
-from __future__ import unicode_literals
-from bottle import template
+from __future__ import absolute_import, unicode_literals
+
 from functools import wraps
 import json
-import jsonpatch
 from time import sleep
+
+from bottle import template
 import six
+
 from test.functional.mock_box.util.http_utils import abort
 
 
+try:
+    import jsonpatch
+except ValueError:
+    # jsonpatch==1.14 on Python 3.6 cannot be imported.
+    # It fails with the following stacktrace:
+    #
+    #       .tox/py/lib/python3.6/site-packages/jsonpatch.py:114: in <module>
+    #           json.load = get_loadjson()
+    #       .tox/py/lib/python3.6/site-packages/jsonpatch.py:108: in get_loadjson
+    #           argspec = inspect.getargspec(json.load)
+    #       lib/python3.6/inspect.py:1039: in getargspec
+    #           raise ValueError("Function has keyword-only arguments or annotations"
+    #       E   ValueError: Function has keyword-only arguments or annotations, use getfullargspec() API which can support them
+    #
+    # Until jsonpatch fixes this issue, we cannot use jsonpatch on Python >=3.6.
+    jsonpatch = None
+
+
 def allow_chaos(method):
     """Decorator for a method to allow erroneous operation."""
     method.call_number = 0
@@ -63,10 +83,19 @@ def xml(method):
 
 
 def patch(operations):
-    json_patch = jsonpatch.JsonPatch(operations)
+    if jsonpatch:
+        json_patch = jsonpatch.JsonPatch(operations)
+
+        def patcher(doc):
+            return json_patch.apply(doc)
+
+    else:
 
-    def patcher(doc):
-        return json_patch.apply(doc)
+        def patcher(doc):
+            # If jsonpatch could not be imported, then `@chaos_utils.patch()`
+            # will be disabled, and will silently return values unmodified,
+            # without applying the JSON patch operations.
+            return doc
 
     def inner(patched_function):
         def patched_inner(*args, **kwargs):
diff --git a/test/unit/util/test_compat.py b/test/unit/util/test_compat.py
index 7fa0f7eeb..42263756b 100644
--- a/test/unit/util/test_compat.py
+++ b/test/unit/util/test_compat.py
@@ -3,7 +3,7 @@
 from __future__ import unicode_literals
 from datetime import datetime, timedelta
 import pytest
-from boxsdk.util.compat import total_seconds
+from boxsdk.util.compat import total_seconds, with_metaclass
 
 
 @pytest.fixture(params=(
@@ -19,3 +19,34 @@ def test_total_seconds(total_seconds_data):
     # pylint:disable=redefined-outer-name
     delta, seconds = total_seconds_data
     assert total_seconds(delta) == seconds
+
+
+def test_with_metaclass():
+
+    class Class1(object):
+        pass
+
+    class Class2(object):
+        pass
+
+    bases = (Class1, Class2)
+
+    class Meta(type):
+        @classmethod
+        def __prepare__(metacls, name, this_bases, **kwds):   # pylint:disable=unused-argument
+            assert this_bases == bases
+            return {}
+
+        def __new__(metacls, name, this_bases, namespace, **kwds):
+            assert this_bases == bases
+            return super(Meta, metacls).__new__(metacls, name, this_bases, namespace, **kwds)
+
+    temporary_class = with_metaclass(Meta, *bases)
+    assert isinstance(temporary_class, Meta)
+    assert temporary_class.__bases__ == bases
+
+    class Subclass(temporary_class):
+        pass
+
+    assert type(Subclass) is Meta   # pylint:disable=unidiomatic-typecheck
+    assert Subclass.__bases__ == bases
diff --git a/test/unit/util/test_enum.py b/test/unit/util/test_enum.py
index 5275636a9..4b67f95bc 100644
--- a/test/unit/util/test_enum.py
+++ b/test/unit/util/test_enum.py
@@ -4,8 +4,8 @@
 
 from enum import Enum
 import pytest
-from six import with_metaclass
 
+from boxsdk.util.compat import with_metaclass
 from boxsdk.util.enum import ExtendableEnumMeta
 from boxsdk.util.ordered_dict import OrderedDict
 
@@ -169,3 +169,7 @@ def test_len(EnumBaseWithSubclassesDefined, enum_members):
 def test_reversed(EnumBaseWithSubclassesDefined):
     EnumBase = EnumBaseWithSubclassesDefined
     assert list(reversed(list(reversed(EnumBase)))) == list(EnumBase)
+
+
+def test_dir(EnumBaseWithSubclassesDefined):
+    assert set(enum_member_names).issubset(dir(EnumBaseWithSubclassesDefined))
diff --git a/tox.ini b/tox.ini
index 6ebc3d35b..b00ce278f 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@ envlist =
   py33,
   py34,
   py35,
+  py36,
   pypy,
   pep8,
   pylint,
@@ -52,7 +53,7 @@ deps = -rrequirements-dev.txt
 [testenv:docs]
 changedir = docs
 deps =
-  sphinx
+  -rrequirements-dev.txt
 commands =
   sphinx-apidoc -f -o source ../boxsdk
   make html