diff --git a/openstackclient/common/clientmanager.py b/openstackclient/common/clientmanager.py
index 85f544e4dc..a0224064da 100644
--- a/openstackclient/common/clientmanager.py
+++ b/openstackclient/common/clientmanager.py
@@ -16,12 +16,10 @@
 """Manage access to the clients, including authenticating when needed."""
 
 import logging
+import pkg_resources
+import sys
 
-from openstackclient.compute import client as compute_client
 from openstackclient.identity import client as identity_client
-from openstackclient.image import client as image_client
-from openstackclient.object import client as object_client
-from openstackclient.volume import client as volume_client
 
 
 LOG = logging.getLogger(__name__)
@@ -42,11 +40,7 @@ class ClientCache(object):
 
 class ClientManager(object):
     """Manages access to API clients, including authentication."""
-    compute = ClientCache(compute_client.make_client)
     identity = ClientCache(identity_client.make_client)
-    image = ClientCache(image_client.make_client)
-    object = ClientCache(object_client.make_client)
-    volume = ClientCache(volume_client.make_client)
 
     def __init__(self, token=None, url=None, auth_url=None, project_name=None,
                  project_id=None, username=None, password=None,
@@ -93,3 +87,26 @@ class ClientManager(object):
             # Hope we were given the correct URL.
             endpoint = self._url
         return endpoint
+
+
+def get_extension_modules(group):
+    """Add extension clients"""
+    mod_list = []
+    for ep in pkg_resources.iter_entry_points(group):
+        LOG.debug('found extension %r' % ep.name)
+
+        __import__(ep.module_name)
+        module = sys.modules[ep.module_name]
+        mod_list.append(module)
+        init_func = getattr(module, 'Initialize', None)
+        if init_func:
+            init_func('x')
+
+        setattr(
+            ClientManager,
+            ep.name,
+            ClientCache(
+                getattr(sys.modules[ep.module_name], 'make_client', None)
+            ),
+        )
+    return mod_list
diff --git a/openstackclient/compute/client.py b/openstackclient/compute/client.py
index 4d3b1b7155..4ccb2f6d40 100644
--- a/openstackclient/compute/client.py
+++ b/openstackclient/compute/client.py
@@ -19,6 +19,8 @@ from openstackclient.common import utils
 
 LOG = logging.getLogger(__name__)
 
+DEFAULT_COMPUTE_API_VERSION = '2'
+API_VERSION_OPTION = 'os_compute_api_version'
 API_NAME = 'compute'
 API_VERSIONS = {
     '1.1': 'novaclient.v1_1.client.Client',
@@ -60,3 +62,17 @@ def make_client(instance):
         client.client.service_catalog = instance._service_catalog
     client.client.auth_token = instance._token
     return client
+
+
+def build_option_parser(parser):
+    """Hook to add global options"""
+    parser.add_argument(
+        '--os-compute-api-version',
+        metavar='<compute-api-version>',
+        default=utils.env(
+            'OS_COMPUTE_API_VERSION',
+            default=DEFAULT_COMPUTE_API_VERSION),
+        help='Compute API version, default=' +
+             DEFAULT_COMPUTE_API_VERSION +
+             ' (Env: OS_COMPUTE_API_VERSION)')
+    return parser
diff --git a/openstackclient/identity/client.py b/openstackclient/identity/client.py
index 4814bc3e2e..305d4cc450 100644
--- a/openstackclient/identity/client.py
+++ b/openstackclient/identity/client.py
@@ -21,6 +21,8 @@ from openstackclient.common import utils
 
 LOG = logging.getLogger(__name__)
 
+DEFAULT_IDENTITY_API_VERSION = '2.0'
+API_VERSION_OPTION = 'os_identity_api_version'
 API_NAME = 'identity'
 API_VERSIONS = {
     '2.0': 'openstackclient.identity.client.IdentityClientv2_0',
diff --git a/openstackclient/image/client.py b/openstackclient/image/client.py
index d56ca3b2ff..9edffded90 100644
--- a/openstackclient/image/client.py
+++ b/openstackclient/image/client.py
@@ -23,6 +23,8 @@ from openstackclient.common import utils
 
 LOG = logging.getLogger(__name__)
 
+DEFAULT_IMAGE_API_VERSION = '1'
+API_VERSION_OPTION = 'os_image_api_version'
 API_NAME = "image"
 API_VERSIONS = {
     "1": "openstackclient.image.client.Client_v1",
@@ -48,6 +50,20 @@ def make_client(instance):
     )
 
 
+def build_option_parser(parser):
+    """Hook to add global options"""
+    parser.add_argument(
+        '--os-image-api-version',
+        metavar='<image-api-version>',
+        default=utils.env(
+            'OS_IMAGE_API_VERSION',
+            default=DEFAULT_IMAGE_API_VERSION),
+        help='Image API version, default=' +
+             DEFAULT_IMAGE_API_VERSION +
+             ' (Env: OS_IMAGE_API_VERSION)')
+    return parser
+
+
 # NOTE(dtroyer): glanceclient.v1.image.ImageManager() doesn't have a find()
 #                method so add one here until the common client libs arrive
 #                A similar subclass will be required for v2
diff --git a/openstackclient/object/client.py b/openstackclient/object/client.py
index a83a5c0a3d..1a5363b17c 100644
--- a/openstackclient/object/client.py
+++ b/openstackclient/object/client.py
@@ -21,7 +21,9 @@ from openstackclient.common import utils
 
 LOG = logging.getLogger(__name__)
 
-API_NAME = 'object-store'
+DEFAULT_OBJECT_API_VERSION = '1'
+API_VERSION_OPTION = 'os_object_api_version'
+API_NAME = 'object'
 API_VERSIONS = {
     '1': 'openstackclient.object.client.ObjectClientv1',
 }
@@ -45,6 +47,20 @@ def make_client(instance):
     return client
 
 
+def build_option_parser(parser):
+    """Hook to add global options"""
+    parser.add_argument(
+        '--os-object-api-version',
+        metavar='<object-api-version>',
+        default=utils.env(
+            'OS_OBJECT_API_VERSION',
+            default=DEFAULT_OBJECT_API_VERSION),
+        help='Object API version, default=' +
+             DEFAULT_OBJECT_API_VERSION +
+             ' (Env: OS_OBJECT_API_VERSION)')
+    return parser
+
+
 class ObjectClientv1(object):
 
     def __init__(
diff --git a/openstackclient/shell.py b/openstackclient/shell.py
index 78e16cd626..f8a47ca664 100644
--- a/openstackclient/shell.py
+++ b/openstackclient/shell.py
@@ -33,15 +33,11 @@ from openstackclient.common import exceptions as exc
 from openstackclient.common import openstackkeyring
 from openstackclient.common import restapi
 from openstackclient.common import utils
+from openstackclient.identity import client as identity_client
 
 
 KEYRING_SERVICE = 'openstack'
 
-DEFAULT_COMPUTE_API_VERSION = '2'
-DEFAULT_IDENTITY_API_VERSION = '2.0'
-DEFAULT_IMAGE_API_VERSION = '1'
-DEFAULT_OBJECT_API_VERSION = '1'
-DEFAULT_VOLUME_API_VERSION = '1'
 DEFAULT_DOMAIN = 'default'
 
 
@@ -86,6 +82,15 @@ class OpenStackShell(app.App):
         # Assume TLS host certificate verification is enabled
         self.verify = True
 
+        # Get list of extension modules
+        self.ext_modules = clientmanager.get_extension_modules(
+            'openstack.cli.extension',
+        )
+
+        # Loop through extensions to get parser additions
+        for mod in self.ext_modules:
+            self.parser = mod.build_option_parser(self.parser)
+
         # NOTE(dtroyer): This hack changes the help action that Cliff
         #                automatically adds to the parser so we can defer
         #                its execution until after the api-versioned commands
@@ -202,51 +207,6 @@ class OpenStackShell(app.App):
             help='Default domain ID, default=' +
                  DEFAULT_DOMAIN +
                  ' (Env: OS_DEFAULT_DOMAIN)')
-        parser.add_argument(
-            '--os-identity-api-version',
-            metavar='<identity-api-version>',
-            default=env(
-                'OS_IDENTITY_API_VERSION',
-                default=DEFAULT_IDENTITY_API_VERSION),
-            help='Identity API version, default=' +
-                 DEFAULT_IDENTITY_API_VERSION +
-                 ' (Env: OS_IDENTITY_API_VERSION)')
-        parser.add_argument(
-            '--os-compute-api-version',
-            metavar='<compute-api-version>',
-            default=env(
-                'OS_COMPUTE_API_VERSION',
-                default=DEFAULT_COMPUTE_API_VERSION),
-            help='Compute API version, default=' +
-                 DEFAULT_COMPUTE_API_VERSION +
-                 ' (Env: OS_COMPUTE_API_VERSION)')
-        parser.add_argument(
-            '--os-image-api-version',
-            metavar='<image-api-version>',
-            default=env(
-                'OS_IMAGE_API_VERSION',
-                default=DEFAULT_IMAGE_API_VERSION),
-            help='Image API version, default=' +
-                 DEFAULT_IMAGE_API_VERSION +
-                 ' (Env: OS_IMAGE_API_VERSION)')
-        parser.add_argument(
-            '--os-object-api-version',
-            metavar='<object-api-version>',
-            default=env(
-                'OS_OBJECT_API_VERSION',
-                default=DEFAULT_OBJECT_API_VERSION),
-            help='Object API version, default=' +
-                 DEFAULT_OBJECT_API_VERSION +
-                 ' (Env: OS_OBJECT_API_VERSION)')
-        parser.add_argument(
-            '--os-volume-api-version',
-            metavar='<volume-api-version>',
-            default=env(
-                'OS_VOLUME_API_VERSION',
-                default=DEFAULT_VOLUME_API_VERSION),
-            help='Volume API version, default=' +
-                 DEFAULT_VOLUME_API_VERSION +
-                 ' (Env: OS_VOLUME_API_VERSION)')
         parser.add_argument(
             '--os-token',
             metavar='<token>',
@@ -270,6 +230,16 @@ class OpenStackShell(app.App):
                             help='Use keyring to store password, '
                                  'default=False (Env: OS_USE_KEYRING)')
 
+        parser.add_argument(
+            '--os-identity-api-version',
+            metavar='<identity-api-version>',
+            default=env(
+                'OS_IDENTITY_API_VERSION',
+                default=identity_client.DEFAULT_IDENTITY_API_VERSION),
+            help='Identity API version, default=' +
+                 identity_client.DEFAULT_IDENTITY_API_VERSION +
+                 ' (Env: OS_IDENTITY_API_VERSION)')
+
         return parser
 
     def authenticate_user(self):
@@ -391,17 +361,20 @@ class OpenStackShell(app.App):
 
         # Stash selected API versions for later
         self.api_version = {
-            'compute': self.options.os_compute_api_version,
             'identity': self.options.os_identity_api_version,
-            'image': self.options.os_image_api_version,
-            'object-store': self.options.os_object_api_version,
-            'volume': self.options.os_volume_api_version,
         }
+        # Loop through extensions to get API versions
+        for mod in self.ext_modules:
+            ver = getattr(self.options, mod.API_VERSION_OPTION, None)
+            if ver:
+                self.api_version[mod.API_NAME] = ver
+                self.log.debug('%s API version %s' % (mod.API_NAME, ver))
 
         # Add the API version-specific commands
         for api in self.api_version.keys():
             version = '.v' + self.api_version[api].replace('.', '_')
             cmd_group = 'openstack.' + api.replace('-', '_') + version
+            self.log.debug('command group %s' % cmd_group)
             self.command_manager.add_command_group(cmd_group)
 
         # Commands that span multiple APIs
@@ -420,6 +393,8 @@ class OpenStackShell(app.App):
         # }
         self.command_manager.add_command_group(
             'openstack.extension')
+        # call InitializeXxx() here
+        # set up additional clients to stuff in to client_manager??
 
         # Handle deferred help and exit
         if self.options.deferred_help:
diff --git a/openstackclient/tests/fakes.py b/openstackclient/tests/fakes.py
index 8ab4546588..bb89f7628f 100644
--- a/openstackclient/tests/fakes.py
+++ b/openstackclient/tests/fakes.py
@@ -49,6 +49,7 @@ class FakeClientManager(object):
         self.compute = None
         self.identity = None
         self.image = None
+        self.object = None
         self.volume = None
         self.auth_ref = None
 
diff --git a/openstackclient/tests/object/v1/fakes.py b/openstackclient/tests/object/v1/fakes.py
index fbc784aae5..37c35d3ba9 100644
--- a/openstackclient/tests/object/v1/fakes.py
+++ b/openstackclient/tests/object/v1/fakes.py
@@ -13,6 +13,10 @@
 #   under the License.
 #
 
+from openstackclient.tests import fakes
+from openstackclient.tests import utils
+
+
 container_name = 'bit-bucket'
 container_bytes = 1024
 container_count = 1
@@ -65,3 +69,19 @@ OBJECT_2 = {
     'content_type': object_content_type_2,
     'last_modified': object_modified_2,
 }
+
+
+class FakeObjectv1Client(object):
+    def __init__(self, **kwargs):
+        self.endpoint = kwargs['endpoint']
+        self.token = kwargs['token']
+
+
+class TestObjectv1(utils.TestCommand):
+    def setUp(self):
+        super(TestObjectv1, self).setUp()
+
+        self.app.client_manager.object = FakeObjectv1Client(
+            endpoint=fakes.AUTH_URL,
+            token=fakes.AUTH_TOKEN,
+        )
diff --git a/openstackclient/tests/object/v1/lib/test_container.py b/openstackclient/tests/object/v1/lib/test_container.py
index 3b9976a1f3..c3fdea72b0 100644
--- a/openstackclient/tests/object/v1/lib/test_container.py
+++ b/openstackclient/tests/object/v1/lib/test_container.py
@@ -19,8 +19,7 @@ import mock
 
 from openstackclient.object.v1.lib import container as lib_container
 from openstackclient.tests.common import test_restapi as restapi
-from openstackclient.tests import fakes
-from openstackclient.tests import utils
+from openstackclient.tests.object.v1 import fakes as object_fakes
 
 
 fake_account = 'q12we34r'
@@ -36,12 +35,10 @@ class FakeClient(object):
         self.token = fake_auth
 
 
-class TestContainer(utils.TestCommand):
+class TestContainer(object_fakes.TestObjectv1):
 
     def setUp(self):
         super(TestContainer, self).setUp()
-        self.app.client_manager = fakes.FakeClientManager()
-        self.app.client_manager.object = FakeClient()
         self.app.restapi = mock.MagicMock()
 
 
@@ -53,7 +50,7 @@ class TestContainerList(TestContainer):
 
         data = lib_container.list_containers(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
         )
 
         # Check expected values
@@ -69,7 +66,7 @@ class TestContainerList(TestContainer):
 
         data = lib_container.list_containers(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             marker='next',
         )
 
@@ -86,7 +83,7 @@ class TestContainerList(TestContainer):
 
         data = lib_container.list_containers(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             limit=5,
         )
 
@@ -103,7 +100,7 @@ class TestContainerList(TestContainer):
 
         data = lib_container.list_containers(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             end_marker='last',
         )
 
@@ -120,7 +117,7 @@ class TestContainerList(TestContainer):
 
         data = lib_container.list_containers(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             prefix='foo/',
         )
 
@@ -147,7 +144,7 @@ class TestContainerList(TestContainer):
 
         data = lib_container.list_containers(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             full_listing=True,
         )
 
@@ -171,7 +168,7 @@ class TestContainerShow(TestContainer):
 
         data = lib_container.show_container(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             'is-name',
         )
 
diff --git a/openstackclient/tests/object/v1/lib/test_object.py b/openstackclient/tests/object/v1/lib/test_object.py
index 0104183e03..ef93877aea 100644
--- a/openstackclient/tests/object/v1/lib/test_object.py
+++ b/openstackclient/tests/object/v1/lib/test_object.py
@@ -19,8 +19,7 @@ import mock
 
 from openstackclient.object.v1.lib import object as lib_object
 from openstackclient.tests.common import test_restapi as restapi
-from openstackclient.tests import fakes
-from openstackclient.tests import utils
+from openstackclient.tests.object.v1 import fakes as object_fakes
 
 
 fake_account = 'q12we34r'
@@ -37,12 +36,10 @@ class FakeClient(object):
         self.token = fake_auth
 
 
-class TestObject(utils.TestCommand):
+class TestObject(object_fakes.TestObjectv1):
 
     def setUp(self):
         super(TestObject, self).setUp()
-        self.app.client_manager = fakes.FakeClientManager()
-        self.app.client_manager.object = FakeClient()
         self.app.restapi = mock.MagicMock()
 
 
@@ -54,7 +51,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
         )
 
@@ -71,7 +68,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             marker='next',
         )
@@ -89,7 +86,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             limit=5,
         )
@@ -107,7 +104,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             end_marker='last',
         )
@@ -125,7 +122,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             delimiter='|',
         )
@@ -146,7 +143,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             prefix='foo/',
         )
@@ -164,7 +161,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             path='next',
         )
@@ -192,7 +189,7 @@ class TestObjectListObjects(TestObject):
 
         data = lib_object.list_objects(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             full_listing=True,
         )
@@ -216,7 +213,7 @@ class TestObjectShowObjects(TestObject):
 
         data = lib_object.show_object(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             fake_object,
         )
@@ -250,7 +247,7 @@ class TestObjectShowObjects(TestObject):
 
         data = lib_object.show_object(
             self.app.restapi,
-            self.app.client_manager.object.endpoint,
+            fake_url,
             fake_container,
             fake_object,
         )
diff --git a/openstackclient/tests/object/v1/test_container.py b/openstackclient/tests/object/v1/test_container.py
index 2090b88029..e4d90fd934 100644
--- a/openstackclient/tests/object/v1/test_container.py
+++ b/openstackclient/tests/object/v1/test_container.py
@@ -16,10 +16,8 @@
 import copy
 import mock
 
-from openstackclient.common import clientmanager
 from openstackclient.object.v1 import container
 from openstackclient.tests.object.v1 import fakes as object_fakes
-from openstackclient.tests import utils
 
 
 AUTH_TOKEN = "foobar"
@@ -32,18 +30,10 @@ class FakeClient(object):
         self.token = AUTH_TOKEN
 
 
-class TestObject(utils.TestCommand):
+class TestObject(object_fakes.TestObjectv1):
     def setUp(self):
         super(TestObject, self).setUp()
 
-        api_version = {"object-store": "1"}
-        self.app.client_manager = clientmanager.ClientManager(
-            token=AUTH_TOKEN,
-            url=AUTH_URL,
-            auth_url=AUTH_URL,
-            api_version=api_version,
-        )
-
 
 class TestObjectClient(TestObject):
 
diff --git a/openstackclient/tests/object/v1/test_object.py b/openstackclient/tests/object/v1/test_object.py
index 52b5ebd086..9987c2d48a 100644
--- a/openstackclient/tests/object/v1/test_object.py
+++ b/openstackclient/tests/object/v1/test_object.py
@@ -16,34 +16,18 @@
 import copy
 import mock
 
-from openstackclient.common import clientmanager
 from openstackclient.object.v1 import object as obj
 from openstackclient.tests.object.v1 import fakes as object_fakes
-from openstackclient.tests import utils
 
 
 AUTH_TOKEN = "foobar"
 AUTH_URL = "http://0.0.0.0"
 
 
-class FakeClient(object):
-    def __init__(self, endpoint=None, **kwargs):
-        self.endpoint = AUTH_URL
-        self.token = AUTH_TOKEN
-
-
-class TestObject(utils.TestCommand):
+class TestObject(object_fakes.TestObjectv1):
     def setUp(self):
         super(TestObject, self).setUp()
 
-        api_version = {"object-store": "1"}
-        self.app.client_manager = clientmanager.ClientManager(
-            token=AUTH_TOKEN,
-            url=AUTH_URL,
-            auth_url=AUTH_URL,
-            api_version=api_version,
-        )
-
 
 class TestObjectClient(TestObject):
 
diff --git a/openstackclient/volume/client.py b/openstackclient/volume/client.py
index 626b23f1c1..e04e8cd7b8 100644
--- a/openstackclient/volume/client.py
+++ b/openstackclient/volume/client.py
@@ -20,6 +20,8 @@ from openstackclient.common import utils
 
 LOG = logging.getLogger(__name__)
 
+DEFAULT_VOLUME_API_VERSION = '1'
+API_VERSION_OPTION = 'os_volume_api_version'
 API_NAME = "volume"
 API_VERSIONS = {
     "1": "cinderclient.v1.client.Client"
@@ -45,3 +47,17 @@ def make_client(instance):
     )
 
     return client
+
+
+def build_option_parser(parser):
+    """Hook to add global options"""
+    parser.add_argument(
+        '--os-volume-api-version',
+        metavar='<volume-api-version>',
+        default=utils.env(
+            'OS_VOLUME_API_VERSION',
+            default=DEFAULT_VOLUME_API_VERSION),
+        help='Volume API version, default=' +
+             DEFAULT_VOLUME_API_VERSION +
+             ' (Env: OS_VOLUME_API_VERSION)')
+    return parser
diff --git a/setup.cfg b/setup.cfg
index 95a585be53..795d965dea 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -27,6 +27,12 @@ console_scripts =
 
 openstack.cli =
 
+openstack.cli.extension =
+    compute = openstackclient.compute.client
+    image = openstackclient.image.client
+    object = openstackclient.object.client
+    volume = openstackclient.volume.client
+
 openstack.common =
     limits_show = openstackclient.common.limits:ShowLimits
     quota_set = openstackclient.common.quota:SetQuota
@@ -240,7 +246,7 @@ openstack.image.v2 =
     image_save = openstackclient.image.v2.image:SaveImage
     image_show = openstackclient.image.v2.image:ShowImage
 
-openstack.object_store.v1 =
+openstack.object.v1 =
     container_list = openstackclient.object.v1.container:ListContainer
     container_show = openstackclient.object.v1.container:ShowContainer
     object_list = openstackclient.object.v1.object:ListObject