diff --git a/cinderclient/tests/v1/fakes.py b/cinderclient/tests/v1/fakes.py
index 2a33ba8..56f086b 100644
--- a/cinderclient/tests/v1/fakes.py
+++ b/cinderclient/tests/v1/fakes.py
@@ -152,6 +152,10 @@ def _stub_transfer(id, base_uri, tenant_id):
     }
 
 
+def _stub_extend(id, new_size):
+    return {'volume_id': '712f4980-5ac1-41e5-9383-390aa7c9f58b'}
+
+
 class FakeClient(fakes.FakeClient, client.Client):
 
     def __init__(self, *args, **kwargs):
@@ -294,6 +298,8 @@ class FakeHTTPClient(base_client.HTTPClient):
             assert body[action] is None
         elif action == 'os-reset_status':
             assert 'status' in body[action]
+        elif action == 'os-extend':
+            assert body[action].keys() == ['new_size']
         else:
             raise AssertionError("Unexpected action: %s" % action)
         return (resp, {}, _body)
diff --git a/cinderclient/tests/v1/test_volumes.py b/cinderclient/tests/v1/test_volumes.py
index 16410c9..768e942 100644
--- a/cinderclient/tests/v1/test_volumes.py
+++ b/cinderclient/tests/v1/test_volumes.py
@@ -69,3 +69,8 @@ class VolumesTest(utils.TestCase):
         keys = ['key1']
         cs.volumes.delete_metadata(1234, keys)
         cs.assert_called('DELETE', '/volumes/1234/metadata/key1')
+
+    def test_extend(self):
+        v = cs.volumes.get('1234')
+        cs.volumes.extend(v, 2)
+        cs.assert_called('POST', '/volumes/1234/action')
diff --git a/cinderclient/v1/shell.py b/cinderclient/v1/shell.py
index f3ac3d9..eeb30ba 100644
--- a/cinderclient/v1/shell.py
+++ b/cinderclient/v1/shell.py
@@ -819,3 +819,15 @@ def do_transfer_show(cs, args):
         info.pop('links')
 
     utils.print_dict(info)
+
+
+@utils.arg('volume', metavar='<volume>', help='ID of the volume to extend.')
+@utils.arg('new_size',
+           metavar='<new-size>',
+           type=int,
+           help='New size of volume in GB')
+@utils.service_type('volume')
+def do_extend(cs, args):
+    """Attempt to extend the size of an existing volume."""
+    volume = _find_volume(cs, args.volume)
+    cs.volumes.extend(volume, args.new_size)
diff --git a/cinderclient/v1/volumes.py b/cinderclient/v1/volumes.py
index 066890d..5f6c566 100644
--- a/cinderclient/v1/volumes.py
+++ b/cinderclient/v1/volumes.py
@@ -105,6 +105,15 @@ class Volume(base.Resource):
         """Update the volume with the provided state."""
         self.manager.reset_state(self, state)
 
+    def extend(self, volume, new_size):
+        """Extend the size of the specified volume.
+
+        :param volume: The UUID of the volume to extend
+        :param new_size: The desired size to extend volume to.
+        """
+
+        self.manager.extend(self, volume, new_size)
+
 
 class VolumeManager(base.ManagerWithFind):
     """
@@ -338,3 +347,8 @@ class VolumeManager(base.ManagerWithFind):
     def reset_state(self, volume, state):
         """Update the provided volume with the provided state."""
         return self._action('os-reset_status', volume, {'status': state})
+
+    def extend(self, volume, new_size):
+        return self._action('os-extend',
+                            base.getid(volume),
+                            {'new_size': new_size})