diff --git a/cliff/command.py b/cliff/command.py
index 643950db..ae66e0e2 100644
--- a/cliff/command.py
+++ b/cliff/command.py
@@ -14,6 +14,7 @@ import abc
 import inspect
 
 import six
+from stevedore import extension
 
 from cliff import _argparse
 
@@ -22,6 +23,12 @@ from cliff import _argparse
 class Command(object):
     """Base class for command plugins.
 
+    When the command is instantiated, it loads extensions from a
+    namespace based on the parent application namespace and the
+    command name::
+
+        app.namespace + '.' + cmd_name.replace(' ', '_')
+
     :param app: Application instance invoking the command.
     :paramtype app: cliff.app.App
 
@@ -36,6 +43,26 @@ class Command(object):
         self.app = app
         self.app_args = app_args
         self.cmd_name = cmd_name
+        self._load_hooks()
+
+    def _load_hooks(self):
+        # Look for command extensions
+        if self.app and self.cmd_name:
+            namespace = '{}.{}'.format(
+                self.app.command_manager.namespace,
+                self.cmd_name.replace(' ', '_')
+            )
+            self._hooks = extension.ExtensionManager(
+                namespace=namespace,
+                invoke_on_load=True,
+                invoke_kwds={
+                    'command': self,
+                },
+            )
+        else:
+            # Setting _hooks to an empty list allows iteration without
+            # checking if there are hooks every time.
+            self._hooks = []
         return
 
     def get_description(self):
@@ -73,6 +100,8 @@ class Command(object):
             prog=prog_name,
             formatter_class=_SmartHelpFormatter,
         )
+        for hook in self._hooks:
+            hook.obj.get_parser(parser)
         return parser
 
     @abc.abstractmethod
diff --git a/cliff/hooks.py b/cliff/hooks.py
new file mode 100644
index 00000000..e8a804ae
--- /dev/null
+++ b/cliff/hooks.py
@@ -0,0 +1,38 @@
+#  Licensed under the Apache License, Version 2.0 (the "License"); you may
+#  not use this file except in compliance with the License. You may obtain
+#  a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#  License for the specific language governing permissions and limitations
+#  under the License.
+
+import abc
+
+import six
+
+
+@six.add_metaclass(abc.ABCMeta)
+class CommandHook(object):
+    """Base class for command hooks.
+
+    :param app: Command instance being invoked
+    :paramtype app: cliff.command.Command
+
+    """
+
+    def __init__(self, command):
+        self.cmd = command
+
+    @abc.abstractmethod
+    def get_parser(self, parser):
+        """Return an :class:`argparse.ArgumentParser`.
+
+        :param parser: An existing ArgumentParser instance to be modified.
+        :paramtype parser: ArgumentParser
+        :returns: ArgumentParser
+        """
+        return parser
diff --git a/cliff/tests/test_command_hooks.py b/cliff/tests/test_command_hooks.py
new file mode 100644
index 00000000..bacc3eba
--- /dev/null
+++ b/cliff/tests/test_command_hooks.py
@@ -0,0 +1,107 @@
+#  Licensed under the Apache License, Version 2.0 (the "License"); you may
+#  not use this file except in compliance with the License. You may obtain
+#  a copy of the License at
+#
+#       http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#  License for the specific language governing permissions and limitations
+#  under the License.
+
+from cliff import app as application
+from cliff import command
+from cliff import commandmanager
+from cliff import hooks
+from cliff.tests import base
+
+import mock
+from stevedore import extension
+
+
+def make_app(**kwargs):
+    cmd_mgr = commandmanager.CommandManager('cliff.tests')
+
+    # Register a command that succeeds
+    cmd = mock.MagicMock(spec=command.Command)
+    command_inst = mock.MagicMock(spec=command.Command)
+    command_inst.run.return_value = 0
+    command.return_value = command_inst
+    cmd_mgr.add_command('mock', cmd)
+
+    # Register a command that fails
+    err_command = mock.Mock(name='err_command', spec=command.Command)
+    err_command_inst = mock.Mock(spec=command.Command)
+    err_command_inst.run = mock.Mock(
+        side_effect=RuntimeError('test exception')
+    )
+    err_command.return_value = err_command_inst
+    cmd_mgr.add_command('error', err_command)
+
+    app = application.App('testing command hooks',
+                          '1',
+                          cmd_mgr,
+                          stderr=mock.Mock(),  # suppress warning messages
+                          **kwargs
+                          )
+    return app
+
+
+class TestCommand(command.Command):
+    """Description of command.
+    """
+
+    def get_parser(self, prog_name):
+        parser = super(TestCommand, self).get_parser(prog_name)
+        return parser
+
+    def take_action(self, parsed_args):
+        return 42
+
+
+class TestHook(hooks.CommandHook):
+
+    def get_parser(self, parser):
+        parser.add_argument('--added-by-hook')
+        return parser
+
+
+class TestCommandLoadHooks(base.TestBase):
+
+    def test_no_app_or_name(self):
+        cmd = TestCommand(None, None)
+        self.assertEqual([], cmd._hooks)
+
+    @mock.patch('stevedore.extension.ExtensionManager')
+    def test_app_and_name(self, em):
+        app = make_app()
+        TestCommand(app, None, cmd_name='test')
+        print(em.mock_calls[0])
+        name, args, kwargs = em.mock_calls[0]
+        print(kwargs)
+        self.assertEqual('cliff.tests.test', kwargs['namespace'])
+
+
+class TestParserHook(base.TestBase):
+
+    def setUp(self):
+        super(TestParserHook, self).setUp()
+        self.app = make_app()
+        self.cmd = TestCommand(self.app, None, cmd_name='test')
+        self.hook = TestHook(self.cmd)
+        self.mgr = extension.ExtensionManager.make_test_instance(
+            [extension.Extension(
+                'parser-hook',
+                None,
+                None,
+                self.hook)],
+        )
+        # Replace the auto-loaded hooks with our explicitly created
+        # manager.
+        self.cmd._hooks = self.mgr
+
+    def test_get_parser(self):
+        parser = self.cmd.get_parser('test')
+        results = parser.parse_args(['--added-by-hook', 'value'])
+        self.assertEqual(results.added_by_hook, 'value')
diff --git a/demoapp/cliffdemo/hook.py b/demoapp/cliffdemo/hook.py
new file mode 100644
index 00000000..09c546c8
--- /dev/null
+++ b/demoapp/cliffdemo/hook.py
@@ -0,0 +1,41 @@
+# All Rights Reserved.
+#
+#    Licensed under the Apache License, Version 2.0 (the "License"); you may
+#    not use this file except in compliance with the License. You may obtain
+#    a copy of the License at
+#
+#         http://www.apache.org/licenses/LICENSE-2.0
+#
+#    Unless required by applicable law or agreed to in writing, software
+#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+#    License for the specific language governing permissions and limitations
+#    under the License.
+
+import logging
+
+from cliff.command import Command
+from cliff.hooks import CommandHook
+
+
+class Hooked(Command):
+    "A command to demonstrate how the hooks work"
+
+    log = logging.getLogger(__name__)
+
+    def take_action(self, parsed_args):
+        self.app.stdout.write('this command has an extension')
+
+
+class Hook(CommandHook):
+    """Hook sample for the 'hooked' command.
+
+    This would normally be provided by a separate package from the
+    main application, but is included in the demo app for simplicity.
+
+    """
+
+    def get_parser(self, parser):
+        print('sample hook get_parser()')
+        parser.add_argument('--added-by-hook')
+        return parser
diff --git a/demoapp/setup.py b/demoapp/setup.py
index dd8695d4..1cd2ce42 100644
--- a/demoapp/setup.py
+++ b/demoapp/setup.py
@@ -60,6 +60,10 @@ setup(
             'file = cliffdemo.show:File',
             'show file = cliffdemo.show:File',
             'unicode = cliffdemo.encoding:Encoding',
+            'hooked = cliffdemo.hook:Hooked',
+        ],
+        'cliff.demo.hooked': [
+            'sample-hook = cliffdemo.hook:Hook',
         ],
     },
 
diff --git a/doc/source/reference/index.rst b/doc/source/reference/index.rst
index 5b67aa18..38abc7ed 100644
--- a/doc/source/reference/index.rst
+++ b/doc/source/reference/index.rst
@@ -29,6 +29,12 @@ Command
 .. autoclass:: cliff.command.Command
    :members:
 
+CommandHook
+-----------
+
+.. autoclass:: cliff.hooks.CommandHook
+   :members:
+
 ShowOne
 -------
 
diff --git a/doc/source/user/demoapp.rst b/doc/source/user/demoapp.rst
index 9dd7b8a4..0edcdbfe 100644
--- a/doc/source/user/demoapp.rst
+++ b/doc/source/user/demoapp.rst
@@ -243,7 +243,6 @@ output formatter and printing the data to the console.
     | Modified Time | 1335569964.0 |
     +---------------+--------------+
 
-
 setup.py
 --------
 
@@ -260,3 +259,40 @@ command namespace so that it only loads the command plugins that it
 should be managing.
 
 .. _distribute: http://packages.python.org/distribute/
+
+Command Extension Hooks
+=======================
+
+Individual subcommands of an application can be extended via hooks
+registered as separate plugins. In the demo application, the
+``hooked`` command has a single extension registered.
+
+The namespace for hooks is a combination of the application namespace
+and the command name. In this case, the application namespace is
+``cliff.demo`` and the command is ``hooked``, so the extension
+namespace is ``cliff.demo.hooked``. If the subcommand name includes
+spaces, they are replaced with underscores ("``_``") to build the
+namespace.
+
+.. literalinclude:: ../../../demoapp/cliffdemo/hook.py
+   :linenos:
+
+Although the ``hooked`` command does not add any arguments to the
+parser it creates, the help output shows that the extension adds a
+single ``--added-by-hook`` option.
+
+::
+
+    (.venv)$ cliffdemo hooked -h
+    sample hook get_parser()
+    usage: cliffdemo hooked [-h] [--added-by-hook ADDED_BY_HOOK]
+
+    A command to demonstrate how the hooks work
+
+    optional arguments:
+      -h, --help            show this help message and exit
+      --added-by-hook ADDED_BY_HOOK
+
+.. seealso::
+
+   :class:`cliff.hooks.CommandHook` -- The API for command hooks.
diff --git a/doc/source/user/introduction.rst b/doc/source/user/introduction.rst
index e0e96159..e9a14ff0 100644
--- a/doc/source/user/introduction.rst
+++ b/doc/source/user/introduction.rst
@@ -19,7 +19,7 @@ fit.
 Cliff Objects
 =============
 
-Cliff is organized around four objects that are combined to create a
+Cliff is organized around five objects that are combined to create a
 useful command line program.
 
 The Application
@@ -50,6 +50,18 @@ responsible for taking action based on instructions from the user. It
 defines its own local argument parser (usually using argparse_) and a
 :func:`take_action` method that does the appropriate work.
 
+The CommandHook
+---------------
+
+The :class:`cliff.hooks.CommandHook` class can extend a Command by
+modifying the command line arguments available, for example to add
+options used by a driver. Each CommandHook subclass must implement the
+full hook API, defined by the base class. Extensions should be
+registered using an entry point namespace based on the application
+namespace and the command name::
+
+  application_namespace + '.' + command_name.replace(' ', '_')
+
 The Interactive Application
 ---------------------------