diff --git a/docs/conf.py b/docs/conf.py
index bd64578..cfd452f 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -366,7 +366,8 @@
 # Example configuration for intersphinx: refer to the Python standard library.
 intersphinx_mapping = {
     'python': ('https://docs.python.org/3.5', None),
-    'urllib3': ('https://urllib3.readthedocs.io/en/latest', None),
+    'urllib3': ('https://urllib3.readthedocs.io/en/stable', None),
+    'requests': ('http://docs.python-requests.org/en/stable', None),
 }
 
 # Autodoc config
diff --git a/docs/reference/google.auth.transport.requests.rst b/docs/reference/google.auth.transport.requests.rst
new file mode 100644
index 0000000..f31830c
--- /dev/null
+++ b/docs/reference/google.auth.transport.requests.rst
@@ -0,0 +1,7 @@
+google.auth.transport.requests module
+=====================================
+
+.. automodule:: google.auth.transport.requests
+    :members:
+    :inherited-members:
+    :show-inheritance:
diff --git a/docs/reference/google.auth.transport.rst b/docs/reference/google.auth.transport.rst
index b9b444c..7767daf 100644
--- a/docs/reference/google.auth.transport.rst
+++ b/docs/reference/google.auth.transport.rst
@@ -11,5 +11,6 @@
 
 .. toctree::
 
+   google.auth.transport.requests
    google.auth.transport.urllib3
 
diff --git a/google/auth/transport/requests.py b/google/auth/transport/requests.py
new file mode 100644
index 0000000..e211090
--- /dev/null
+++ b/google/auth/transport/requests.py
@@ -0,0 +1,194 @@
+# Copyright 2016 Google Inc.
+#
+# 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.
+
+"""Transport adapter for Requests."""
+
+from __future__ import absolute_import
+
+import logging
+
+
+import requests
+import requests.exceptions
+
+from google.auth import exceptions
+from google.auth import transport
+
+_LOGGER = logging.getLogger(__name__)
+
+
+class _Response(transport.Response):
+    """Requests transport response adapter.
+
+    Args:
+        response (requests.Response): The raw Requests response.
+    """
+    def __init__(self, response):
+        self._response = response
+
+    @property
+    def status(self):
+        return self._response.status_code
+
+    @property
+    def headers(self):
+        return self._response.headers
+
+    @property
+    def data(self):
+        return self._response.content
+
+
+class Request(transport.Request):
+    """Requests request adapter.
+
+    This class is used internally for making requests using various transports
+    in a consistent way. If you use :class:`AuthorizedSession` you do not need
+    to construct or use this class directly.
+
+    This class can be useful if you want to manually refresh a
+    :class:`~google.auth.credentials.Credentials` instance::
+
+        import google.auth.transport.requests
+        import requests
+
+        request = google.auth.transport.requests.Request()
+
+        credentials.refresh(request)
+
+    Args:
+        session (requests.Session): An instance :class:`requests.Session` used
+            to make HTTP requests. If not specified, a session will be created.
+
+    .. automethod:: __call__
+    """
+    def __init__(self, session=None):
+        if not session:
+            session = requests.Session()
+
+        self.session = session
+
+    def __call__(self, url, method='GET', body=None, headers=None,
+                 timeout=None, **kwargs):
+        """Make an HTTP request using requests.
+
+        Args:
+            url (str): The URI to be requested.
+            method (str): The HTTP method to use for the request. Defaults
+                to 'GET'.
+            body (bytes): The payload / body in HTTP request.
+            headers (Mapping[str, str]): Request headers.
+            timeout (Optional[int]): The number of seconds to wait for a
+                response from the server. If not specified or if None, the
+                requests default timeout will be used.
+            kwargs: Additional arguments passed through to the underlying
+                requests :meth:`~requests.Session.request` method.
+
+        Returns:
+            google.auth.transport.Response: The HTTP response.
+
+        Raises:
+            google.auth.exceptions.TransportError: If any exception occurred.
+        """
+        try:
+            _LOGGER.debug('Making request: %s %s', method, url)
+            response = self.session.request(
+                method, url, data=body, headers=headers, timeout=timeout,
+                **kwargs)
+            return _Response(response)
+        except requests.exceptions.RequestException as exc:
+            raise exceptions.TransportError(exc)
+
+
+class AuthorizedSession(requests.Session):
+    """A Requests Session class with credentials.
+
+    This class is used to perform requests to API endpoints that require
+    authorization::
+
+        from google.auth.transport.requests import AuthorizedSession
+
+        authed_session = AuthorizedSession(credentials)
+
+        response = authed_session.request(
+            'GET', 'https://www.googleapis.com/storage/v1/b')
+
+    The underlying :meth:`request` implementation handles adding the
+    credentials' headers to the request and refreshing credentials as needed.
+
+    Args:
+        credentials (google.auth.credentials.Credentials): The credentials to
+            add to the request.
+        refresh_status_codes (Sequence[int]): Which HTTP status codes indicate
+            that credentials should be refreshed and the request should be
+            retried.
+        max_refresh_attempts (int): The maximum number of times to attempt to
+            refresh the credentials and retry the request.
+        kwargs: Additional arguments passed to the :class:`requests.Session`
+            constructor.
+    """
+    def __init__(self, credentials,
+                 refresh_status_codes=transport.DEFAULT_REFRESH_STATUS_CODES,
+                 max_refresh_attempts=transport.DEFAULT_MAX_REFRESH_ATTEMPTS,
+                 **kwargs):
+        super(AuthorizedSession, self).__init__(**kwargs)
+        self.credentials = credentials
+        self._refresh_status_codes = refresh_status_codes
+        self._max_refresh_attempts = max_refresh_attempts
+        # Request instance used by internal methods (for example,
+        # credentials.refresh).
+        # Do not pass `self` as the session here, as it can lead to infinite
+        # recursion.
+        self._auth_request = Request()
+
+    def request(self, method, url, data=None, headers=None, **kwargs):
+        """Implementation of Requests' request."""
+
+        # Use a kwarg for this instead of an attribute to maintain
+        # thread-safety.
+        _credential_refresh_attempt = kwargs.pop(
+            '_credential_refresh_attempt', 0)
+
+        # Make a copy of the headers. They will be modified by the credentials
+        # and we want to pass the original headers if we recurse.
+        request_headers = headers.copy() if headers is not None else {}
+
+        self.credentials.before_request(
+            self._auth_request, method, url, request_headers)
+
+        response = super(AuthorizedSession, self).request(
+            method, url, data=data, headers=request_headers, **kwargs)
+
+        # If the response indicated that the credentials needed to be
+        # refreshed, then refresh the credentials and re-attempt the
+        # request.
+        # A stored token may expire between the time it is retrieved and
+        # the time the request is made, so we may need to try twice.
+        if (response.status_code in self._refresh_status_codes
+                and _credential_refresh_attempt < self._max_refresh_attempts):
+
+            _LOGGER.info(
+                'Refreshing credentials due to a %s response. Attempt %s/%s.',
+                response.status_code, _credential_refresh_attempt + 1,
+                self._max_refresh_attempts)
+
+            self.credentials.refresh(self._auth_request)
+
+            # Recurse. Pass in the original headers, not our modified set.
+            return self.request(
+                method, url, data=data, headers=headers,
+                _credential_refresh_attempt=_credential_refresh_attempt + 1,
+                **kwargs)
+
+        return response
diff --git a/system_tests/conftest.py b/system_tests/conftest.py
index afa7854..d0f7cc0 100644
--- a/system_tests/conftest.py
+++ b/system_tests/conftest.py
@@ -16,8 +16,10 @@
 import os
 
 from google.auth import _helpers
+import google.auth.transport.requests
 import google.auth.transport.urllib3
 import pytest
+import requests
 import urllib3
 
 
@@ -25,7 +27,9 @@
 DATA_DIR = os.path.join(HERE, 'data')
 SERVICE_ACCOUNT_FILE = os.path.join(DATA_DIR, 'service_account.json')
 AUTHORIZED_USER_FILE = os.path.join(DATA_DIR, 'authorized_user.json')
-HTTP = urllib3.PoolManager(retries=False)
+URLLIB3_HTTP = urllib3.PoolManager(retries=False)
+REQUESTS_SESSION = requests.Session()
+REQUESTS_SESSION.verify = False
 TOKEN_INFO_URL = 'https://www.googleapis.com/oauth2/v3/tokeninfo'
 
 
@@ -41,10 +45,13 @@
     yield AUTHORIZED_USER_FILE
 
 
-@pytest.fixture
-def http_request():
+@pytest.fixture(params=['urllib3', 'requests'])
+def http_request(request):
     """A transport.request object."""
-    yield google.auth.transport.urllib3.Request(HTTP)
+    if request.param == 'urllib3':
+        yield google.auth.transport.urllib3.Request(URLLIB3_HTTP)
+    elif request.param == 'requests':
+        yield google.auth.transport.requests.Request(REQUESTS_SESSION)
 
 
 @pytest.fixture
diff --git a/tests/transport/test_requests.py b/tests/transport/test_requests.py
new file mode 100644
index 0000000..4be4668
--- /dev/null
+++ b/tests/transport/test_requests.py
@@ -0,0 +1,118 @@
+# Copyright 2016 Google Inc.
+#
+# 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 mock
+import requests
+import requests.adapters
+from six.moves import http_client
+
+import google.auth.transport.requests
+from tests.transport import compliance
+
+
+class TestRequestResponse(compliance.RequestResponseTests):
+    def make_request(self):
+        return google.auth.transport.requests.Request()
+
+    def test_timeout(self):
+        http = mock.Mock()
+        request = google.auth.transport.requests.Request(http)
+        request(url='http://example.com', method='GET', timeout=5)
+
+        assert http.request.call_args[1]['timeout'] == 5
+
+
+class MockCredentials(object):
+    def __init__(self, token='token'):
+        self.token = token
+
+    def apply(self, headers):
+        headers['authorization'] = self.token
+
+    def before_request(self, request, method, url, headers):
+        self.apply(headers)
+
+    def refresh(self, request):
+        self.token += '1'
+
+
+class MockAdapter(requests.adapters.BaseAdapter):
+    def __init__(self, responses, headers=None):
+        self.responses = responses
+        self.requests = []
+        self.headers = headers or {}
+
+    def send(self, request, **kwargs):
+        self.requests.append(request)
+        return self.responses.pop(0)
+
+
+def make_response(status=http_client.OK, data=None):
+    response = requests.Response()
+    response.status_code = status
+    response._content = data
+    return response
+
+
+class TestAuthorizedHttp(object):
+    TEST_URL = 'http://example.com/'
+
+    def test_constructor(self):
+        authed_session = google.auth.transport.requests.AuthorizedSession(
+            mock.sentinel.credentials)
+
+        assert authed_session.credentials == mock.sentinel.credentials
+
+    def test_request_no_refresh(self):
+        mock_credentials = mock.Mock(wraps=MockCredentials())
+        mock_response = make_response()
+        mock_adapter = MockAdapter([mock_response])
+
+        authed_session = google.auth.transport.requests.AuthorizedSession(
+            mock_credentials)
+        authed_session.mount(self.TEST_URL, mock_adapter)
+
+        response = authed_session.request('GET', self.TEST_URL)
+
+        assert response == mock_response
+        assert mock_credentials.before_request.called
+        assert not mock_credentials.refresh.called
+        assert len(mock_adapter.requests) == 1
+        assert mock_adapter.requests[0].url == self.TEST_URL
+        assert mock_adapter.requests[0].headers['authorization'] == 'token'
+
+    def test_request_refresh(self):
+        mock_credentials = mock.Mock(wraps=MockCredentials())
+        mock_final_response = make_response(status=http_client.OK)
+        # First request will 401, second request will succeed.
+        mock_adapter = MockAdapter([
+            make_response(status=http_client.UNAUTHORIZED),
+            mock_final_response])
+
+        authed_session = google.auth.transport.requests.AuthorizedSession(
+            mock_credentials)
+        authed_session.mount(self.TEST_URL, mock_adapter)
+
+        response = authed_session.request('GET', self.TEST_URL)
+
+        assert response == mock_final_response
+        assert mock_credentials.before_request.call_count == 2
+        assert mock_credentials.refresh.called
+        assert len(mock_adapter.requests) == 2
+
+        assert mock_adapter.requests[0].url == self.TEST_URL
+        assert mock_adapter.requests[0].headers['authorization'] == 'token'
+
+        assert mock_adapter.requests[1].url == self.TEST_URL
+        assert mock_adapter.requests[1].headers['authorization'] == 'token1'
diff --git a/tox.ini b/tox.ini
index 427f2b7..1ef803c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -10,6 +10,7 @@
   pytest-localserver
   urllib3
   certifi
+  requests
 commands =
   py.test --cov=google.auth --cov=google.oauth2 --cov=tests {posargs:tests}