diff --git a/apiclient/http.py b/apiclient/http.py
index cd279b1..28dba64 100644
--- a/apiclient/http.py
+++ b/apiclient/http.py
@@ -617,6 +617,7 @@
     self.http = http
     self.postproc = postproc
     self.resumable = resumable
+    self.response_callbacks = []
     self._in_error_state = False
 
     # Pull the multipart boundary out of the content-type header.
@@ -673,10 +674,24 @@
 
       resp, content = http.request(str(self.uri), method=str(self.method),
                                    body=self.body, headers=self.headers)
+      for callback in self.response_callbacks:
+        callback(resp)
       if resp.status >= 300:
         raise HttpError(resp, content, uri=self.uri)
     return self.postproc(resp, content)
 
+  @util.positional(2)
+  def add_response_callback(self, cb):
+    """add_response_headers_callback
+
+    Args:
+      cb: Callback to be called on receiving the response headers, of signature:
+
+      def cb(resp):
+        # Where resp is an instance of httplib2.Response
+    """
+    self.response_callbacks.append(cb)
+
   @util.positional(1)
   def next_chunk(self, http=None):
     """Execute the next step of a resumable upload.
diff --git a/apiclient/push.py b/apiclient/push.py
new file mode 100644
index 0000000..c520faf
--- /dev/null
+++ b/apiclient/push.py
@@ -0,0 +1,274 @@
+# 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.
+
+"""Push notifications support.
+
+This code is based on experimental APIs and is subject to change.
+"""
+
+__author__ = 'afshar@google.com (Ali Afshar)'
+
+import binascii
+import collections
+import os
+import urllib
+
+SUBSCRIBE = 'X-GOOG-SUBSCRIBE'
+SUBSCRIPTION_ID = 'X-GOOG-SUBSCRIPTION-ID'
+TOPIC_ID = 'X-GOOG-TOPIC-ID'
+TOPIC_URI = 'X-GOOG-TOPIC-URI'
+CLIENT_TOKEN = 'X-GOOG-CLIENT-TOKEN'
+EVENT_TYPE = 'X-GOOG-EVENT-TYPE'
+UNSUBSCRIBE = 'X-GOOG-UNSUBSCRIBE'
+
+
+class InvalidSubscriptionRequestError(ValueError):
+  """The request cannot be subscribed."""
+
+
+def new_token():
+  """Gets a random token for use as a client_token in push notifications.
+
+  Returns:
+    str, a new random token.
+  """
+  return binascii.hexlify(os.urandom(32))
+
+
+class Channel(object):
+  """Base class for channel types."""
+
+  def __init__(self, channel_type, channel_args):
+    """Create a new Channel.
+
+    You probably won't need to create this channel manually, since there are
+    subclassed Channel for each specific type with a more customized set of
+    arguments to pass. However, you may wish to just create it manually here.
+
+    Args:
+      channel_type: str, the type of channel.
+      channel_args: dict, arguments to pass to the channel.
+    """
+    self.channel_type = channel_type
+    self.channel_args = channel_args
+
+  def as_header_value(self):
+    """Create the appropriate header for this channel.
+
+    Returns:
+      str encoded channel description suitable for use as a header.
+    """
+    return '%s?%s' % (self.channel_type, urllib.urlencode(self.channel_args))
+
+  def write_header(self, headers):
+    """Write the appropriate subscribe header to a headers dict.
+
+    Args:
+      headers: dict, headers to add subscribe header to.
+    """
+    headers[SUBSCRIBE] = self.as_header_value()
+
+
+class WebhookChannel(Channel):
+  """Channel for registering web hook notifications."""
+
+  def __init__(self, url, app_engine=False):
+    """Create a new WebhookChannel
+
+    Args:
+      url: str, URL to post notifications to.
+      app_engine: bool, default=False, whether the destination for the
+      notifications is an App Engine application.
+    """
+    super(WebhookChannel, self).__init__(
+        channel_type='web_hook',
+        channel_args={
+            'url': url,
+            'app_engine': app_engine and 'true' or 'false',
+        }
+    )
+
+
+class Headers(collections.defaultdict):
+  """Headers for managing subscriptions."""
+
+
+  ALL_HEADERS = set([SUBSCRIBE, SUBSCRIPTION_ID, TOPIC_ID, TOPIC_URI,
+                     CLIENT_TOKEN, EVENT_TYPE, UNSUBSCRIBE])
+
+  def __init__(self):
+    """Create a new subscription configuration instance."""
+    collections.defaultdict.__init__(self, str)
+
+  def __setitem__(self, key, value):
+    """Set a header value, ensuring the key is an allowed value.
+
+    Args:
+      key: str, the header key.
+      value: str, the header value.
+    Raises:
+      ValueError if key is not one of the accepted headers.
+    """
+    normal_key = self._normalize_key(key)
+    if normal_key not in self.ALL_HEADERS:
+      raise ValueError('Header name must be one of %s.' % self.ALL_HEADERS)
+    else:
+      return collections.defaultdict.__setitem__(self, normal_key, value)
+
+  def __getitem__(self, key):
+    """Get a header value, normalizing the key case.
+
+    Args:
+      key: str, the header key.
+    Returns:
+      String header value.
+    Raises:
+      KeyError if the key is not one of the accepted headers.
+    """
+    normal_key = self._normalize_key(key)
+    if normal_key not in self.ALL_HEADERS:
+      raise ValueError('Header name must be one of %s.' % self.ALL_HEADERS)
+    else:
+      return collections.defaultdict.__getitem__(self, normal_key)
+
+  def _normalize_key(self, key):
+    """Normalize a header name for use as a key."""
+    return key.upper()
+
+  def items(self):
+    """Generator for each header."""
+    for header in self.ALL_HEADERS:
+      value = self[header]
+      if value:
+        yield header, value
+
+  def write(self, headers):
+    """Applies the subscription headers.
+
+    Args:
+      headers: dict of headers to insert values into.
+    """
+    for header, value in self.items():
+      headers[header.lower()] = value
+
+  def read(self, headers):
+    """Read from headers.
+
+    Args:
+      headers: dict of headers to read from.
+    """
+    for header in self.ALL_HEADERS:
+      if header.lower() in headers:
+        self[header] = headers[header.lower()]
+
+
+class Subscription(object):
+  """Information about a subscription."""
+
+  def __init__(self):
+    """Create a new Subscription."""
+    self.headers = Headers()
+
+  @classmethod
+  def for_request(cls, request, channel, client_token=None):
+    """Creates a subscription and attaches it to a request.
+
+    Args:
+      request: An http.HttpRequest to modify for making a subscription.
+      channel: A apiclient.push.Channel describing the subscription to
+               create.
+      client_token: (optional) client token to verify the notification.
+
+    Returns:
+      New subscription object.
+    """
+    subscription = cls.for_channel(channel=channel, client_token=client_token)
+    subscription.headers.write(request.headers)
+    if request.method != 'GET':
+      raise InvalidSubscriptionRequestError(
+          'Can only subscribe to requests which are GET.')
+    request.method = 'POST'
+
+    def _on_response(response, subscription=subscription):
+      """Called with the response headers. Reads the subscription headers."""
+      subscription.headers.read(response)
+
+    request.add_response_callback(_on_response)
+    return subscription
+
+  @classmethod
+  def for_channel(cls, channel, client_token=None):
+    """Alternate constructor to create a subscription from a channel.
+
+    Args:
+      channel: A apiclient.push.Channel describing the subscription to
+               create.
+      client_token: (optional) client token to verify the notification.
+
+    Returns:
+      New subscription object.
+    """
+    subscription = cls()
+    channel.write_header(subscription.headers)
+    if client_token is None:
+      client_token = new_token()
+    subscription.headers[SUBSCRIPTION_ID] = new_token()
+    subscription.headers[CLIENT_TOKEN] = client_token
+    return subscription
+
+  def verify(self, headers):
+    """Verifies that a webhook notification has the correct client_token.
+
+    Args:
+      headers: dict of request headers for a push notification.
+
+    Returns:
+      Boolean value indicating whether the notification is verified.
+    """
+    new_subscription = Subscription()
+    new_subscription.headers.read(headers)
+    return new_subscription.client_token == self.client_token
+
+  @property
+  def subscribe(self):
+    """Subscribe header value."""
+    return self.headers[SUBSCRIBE]
+
+  @property
+  def subscription_id(self):
+    """Subscription ID header value."""
+    return self.headers[SUBSCRIPTION_ID]
+
+  @property
+  def topic_id(self):
+    """Topic ID header value."""
+    return self.headers[TOPIC_ID]
+
+  @property
+  def topic_uri(self):
+    """Topic URI header value."""
+    return self.headers[TOPIC_URI]
+
+  @property
+  def client_token(self):
+    """Client Token header value."""
+    return self.headers[CLIENT_TOKEN]
+
+  @property
+  def event_type(self):
+    """Event Type header value."""
+    return self.headers[EVENT_TYPE]
+
+  @property
+  def unsubscribe(self):
+    """Unsuscribe header value."""
+    return self.headers[UNSUBSCRIBE]
diff --git a/tests/test_http.py b/tests/test_http.py
index 81248eb..7fc9c51 100644
--- a/tests/test_http.py
+++ b/tests/test_http.py
@@ -827,5 +827,27 @@
     s =  _StreamSlice(self.stream, 2, 1)
     self.assertEqual('2', s.read(-1))
 
+
+class TestResponseCallback(unittest.TestCase):
+  """Test adding callbacks to responses."""
+
+  def test_ensure_response_callback(self):
+    m = JsonModel()
+    request = HttpRequest(
+        None,
+        m.response,
+        'https://www.googleapis.com/someapi/v1/collection/?foo=bar',
+        method='POST',
+        body='{}',
+        headers={'content-type': 'application/json'})
+    h = HttpMockSequence([ ({'status': 200}, '{}')])
+    responses = []
+    def _on_response(resp, responses=responses):
+      responses.append(resp)
+    request.add_response_callback(_on_response)
+    request.execute(http=h)
+    self.assertEqual(1, len(responses))
+
+
 if __name__ == '__main__':
   unittest.main()
diff --git a/tests/test_push.py b/tests/test_push.py
new file mode 100644
index 0000000..5a42835
--- /dev/null
+++ b/tests/test_push.py
@@ -0,0 +1,272 @@
+# 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.
+
+"""Push notifications tests."""
+
+__author__ = 'afshar@google.com (Ali Afshar)'
+
+import unittest
+
+from apiclient import push
+from apiclient import model
+from apiclient import http
+
+
+class ClientTokenGeneratorTest(unittest.TestCase):
+
+  def test_next(self):
+    t = push.new_token()
+    self.assertTrue(t)
+
+
+class ChannelTest(unittest.TestCase):
+
+  def test_creation_noargs(self):
+    c = push.Channel(channel_type='my_channel_type', channel_args={})
+    self.assertEqual('my_channel_type', c.channel_type)
+    self.assertEqual({}, c.channel_args)
+
+  def test_creation_args(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b'})
+    self.assertEqual('my_channel_type', c.channel_type)
+    self.assertEqual({'a':'b'}, c.channel_args)
+
+  def test_as_header_value_noargs(self):
+    c = push.Channel(channel_type='my_channel_type', channel_args={})
+    self.assertEqual('my_channel_type?', c.as_header_value())
+
+  def test_as_header_value_args(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b'})
+    self.assertEqual('my_channel_type?a=b', c.as_header_value())
+
+  def test_as_header_value_args_space(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b c'})
+    self.assertEqual('my_channel_type?a=b+c', c.as_header_value())
+
+  def test_as_header_value_args_escape(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b%c'})
+    self.assertEqual('my_channel_type?a=b%25c', c.as_header_value())
+
+  def test_write_header_noargs(self):
+    c = push.Channel(channel_type='my_channel_type', channel_args={})
+    headers = {}
+    c.write_header(headers)
+    self.assertEqual('my_channel_type?', headers['X-GOOG-SUBSCRIBE'])
+
+  def test_write_header_args(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b'})
+    headers = {}
+    c.write_header(headers)
+    self.assertEqual('my_channel_type?a=b', headers['X-GOOG-SUBSCRIBE'])
+
+  def test_write_header_args_space(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b c'})
+    headers = {}
+    c.write_header(headers)
+    self.assertEqual('my_channel_type?a=b+c', headers['X-GOOG-SUBSCRIBE'])
+
+  def test_write_header_args_escape(self):
+    c = push.Channel(channel_type='my_channel_type',
+                         channel_args={'a': 'b%c'})
+    headers = {}
+    c.write_header(headers)
+    self.assertEqual('my_channel_type?a=b%25c', headers['X-GOOG-SUBSCRIBE'])
+
+
+class WebhookChannelTest(unittest.TestCase):
+
+  def test_creation_no_appengine(self):
+    c = push.WebhookChannel('http://example.org')
+    self.assertEqual('web_hook?url=http%3A%2F%2Fexample.org&app_engine=false',
+                     c.as_header_value())
+
+  def test_creation_appengine(self):
+    c = push.WebhookChannel('http://example.org', app_engine=True)
+    self.assertEqual('web_hook?url=http%3A%2F%2Fexample.org&app_engine=true',
+                     c.as_header_value())
+
+
+class HeadersTest(unittest.TestCase):
+
+  def test_creation(self):
+    h = push.Headers()
+    self.assertEqual('', h[push.SUBSCRIBE])
+
+  def test_items(self):
+    h = push.Headers()
+    h[push.SUBSCRIBE] = 'my_channel_type'
+    self.assertEqual([(push.SUBSCRIBE, 'my_channel_type')], list(h.items()))
+
+  def test_items_non_whitelisted(self):
+    h = push.Headers()
+    def set_bad_header(h=h):
+      h['X-Banana'] = 'my_channel_type'
+    self.assertRaises(ValueError, set_bad_header)
+
+  def test_read(self):
+    h = push.Headers()
+    h.read({'x-goog-subscribe': 'my_channel_type'})
+    self.assertEqual([(push.SUBSCRIBE, 'my_channel_type')], list(h.items()))
+
+  def test_read_non_whitelisted(self):
+    h = push.Headers()
+    h.read({'X-Banana': 'my_channel_type'})
+    self.assertEqual([], list(h.items()))
+
+  def test_write(self):
+    h = push.Headers()
+    h[push.SUBSCRIBE] = 'my_channel_type'
+    headers = {}
+    h.write(headers)
+    self.assertEqual({'x-goog-subscribe': 'my_channel_type'}, headers)
+
+
+class SubscriptionTest(unittest.TestCase):
+
+  def test_create(self):
+    s = push.Subscription()
+    self.assertEqual('', s.client_token)
+
+  def test_create_for_channnel(self):
+    c = push.WebhookChannel('http://example.org')
+    s = push.Subscription.for_channel(c)
+    self.assertTrue(s.client_token)
+    self.assertEqual('web_hook?url=http%3A%2F%2Fexample.org&app_engine=false',
+                     s.subscribe)
+
+  def test_create_for_channel_client_token(self):
+    c = push.WebhookChannel('http://example.org')
+    s = push.Subscription.for_channel(c, client_token='my_token')
+    self.assertEqual('my_token', s.client_token)
+    self.assertEqual('web_hook?url=http%3A%2F%2Fexample.org&app_engine=false',
+                     s.subscribe)
+
+  def test_subscribe(self):
+    s = push.Subscription()
+    s.headers[push.SUBSCRIBE] = 'my_header'
+    self.assertEqual('my_header', s.subscribe)
+
+  def test_subscription_id(self):
+    s = push.Subscription()
+    s.headers[push.SUBSCRIPTION_ID] = 'my_header'
+    self.assertEqual('my_header', s.subscription_id)
+
+  def test_subscription_id_set(self):
+    c = push.WebhookChannel('http://example.org')
+    s = push.Subscription.for_channel(c)
+    self.assertTrue(s.subscription_id)
+
+  def test_topic_id(self):
+    s = push.Subscription()
+    s.headers[push.TOPIC_ID] = 'my_header'
+    self.assertEqual('my_header', s.topic_id)
+
+  def test_topic_uri(self):
+    s = push.Subscription()
+    s.headers[push.TOPIC_URI] = 'my_header'
+    self.assertEqual('my_header', s.topic_uri)
+
+  def test_client_token(self):
+    s = push.Subscription()
+    s.headers[push.CLIENT_TOKEN] = 'my_header'
+    self.assertEqual('my_header', s.client_token)
+
+  def test_event_type(self):
+    s = push.Subscription()
+    s.headers[push.EVENT_TYPE] = 'my_header'
+    self.assertEqual('my_header', s.event_type)
+
+  def test_unsubscribe(self):
+    s = push.Subscription()
+    s.headers[push.UNSUBSCRIBE] = 'my_header'
+    self.assertEqual('my_header', s.unsubscribe)
+
+  def test_do_subscribe(self):
+    m = model.JsonModel()
+    request = http.HttpRequest(
+        None,
+        m.response,
+        'https://www.googleapis.com/someapi/v1/collection/?foo=bar',
+        method='GET',
+        body='{}',
+        headers={'content-type': 'application/json'})
+    h = http.HttpMockSequence([
+        ({'status': 200,
+          'X-Goog-Subscription-ID': 'my_subscription'},
+          '{}')])
+    c = push.Channel('my_channel', {})
+    s = push.Subscription.for_request(request, c)
+    request.execute(http=h)
+    self.assertEqual('my_subscription', s.subscription_id)
+
+  def test_subscribe_with_token(self):
+    m = model.JsonModel()
+    request = http.HttpRequest(
+        None,
+        m.response,
+        'https://www.googleapis.com/someapi/v1/collection/?foo=bar',
+        method='GET',
+        body='{}',
+        headers={'content-type': 'application/json'})
+    h = http.HttpMockSequence([
+        ({'status': 200,
+          'X-Goog-Subscription-ID': 'my_subscription'},
+          '{}')])
+    c = push.Channel('my_channel', {})
+    s = push.Subscription.for_request(request, c, client_token='my_token')
+    request.execute(http=h)
+    self.assertEqual('my_subscription', s.subscription_id)
+    self.assertEqual('my_token', s.client_token)
+
+  def test_verify_good_token(self):
+    s = push.Subscription()
+    s.headers['X-Goog-Client-Token'] = '123'
+    notification_headers = {'x-goog-client-token': '123'}
+    self.assertTrue(s.verify(notification_headers))
+
+  def test_verify_bad_token(self):
+    s = push.Subscription()
+    s.headers['X-Goog-Client-Token'] = '321'
+    notification_headers = {'x-goog-client-token': '123'}
+    self.assertFalse(s.verify(notification_headers))
+
+  def test_request_is_post(self):
+    m = model.JsonModel()
+    request = http.HttpRequest(
+        None,
+        m.response,
+        'https://www.googleapis.com/someapi/v1/collection/?foo=bar',
+        method='GET',
+        body='{}',
+        headers={'content-type': 'application/json'})
+    c = push.Channel('my_channel', {})
+    push.Subscription.for_request(request, c)
+    self.assertEqual('POST', request.method)
+
+  def test_non_get_error(self):
+    m = model.JsonModel()
+    request = http.HttpRequest(
+        None,
+        m.response,
+        'https://www.googleapis.com/someapi/v1/collection/?foo=bar',
+        method='POST',
+        body='{}',
+        headers={'content-type': 'application/json'})
+    c = push.Channel('my_channel', {})
+    self.assertRaises(push.InvalidSubscriptionRequestError,
+                      push.Subscription.for_request, request, c)