diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index fdcc19b448f2..741724e8f962 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -248,8 +248,12 @@ Running System Tests
 
 .. _emulators: https://cloud.google.com/sdk/gcloud/reference/beta/emulators/
 
-- To run the ``pubsub`` system tests with an emulator, first start the
-  emulator and take note of the process ID::
+- To run the system tests with the ``pubsub`` emulator::
+
+   $ tox -e pubsub-emulator
+
+  If you'd like to run them directly (outside of a ``tox`` environment), first
+  start the emulator and take note of the process ID::
 
    $ gcloud beta emulators pubsub start &
    [1] 44444
@@ -262,7 +266,7 @@ Running System Tests
 
   using these environment variables run the emulator::
 
-   $ DATASTORE_HOST=http://localhost:8897 \
+   $ PUBSUB_EMULATOR_HOST=http://localhost:8897 \
    >   python system_tests/run_system_test.py \
    >   --package=pubsub
 
diff --git a/scripts/datastore_emulator.py b/scripts/datastore_emulator.py
deleted file mode 100644
index b91c51d655c2..000000000000
--- a/scripts/datastore_emulator.py
+++ /dev/null
@@ -1,63 +0,0 @@
-# Copyright 2016 Google Inc. 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.
-
-"""Run datastore system tests locally with the datastore emulator.
-
-First makes system calls to spawn the datastore emulator and get
-the local environment variables needed for it. Then calls the
-datastore system tests.
-"""
-
-
-import os
-import subprocess
-
-from gcloud.environment_vars import GCD_DATASET
-from gcloud.environment_vars import GCD_HOST
-from system_tests.run_system_test import run_module_tests
-
-
-_START_CMD = ('gcloud', 'beta', 'emulators', 'datastore', 'start')
-_ENV_INIT_CMD = ('gcloud', 'beta', 'emulators', 'datastore', 'env-init')
-_DATASET_PREFIX = 'export ' + GCD_DATASET + '='
-_HOST_LINE_PREFIX = 'export ' + GCD_HOST + '='
-
-
-def main():
-    """Spawn an emulator instance and run the datastore system tests."""
-    # Ignore stdin and stdout, don't pollute the user's output with them.
-    proc_start = subprocess.Popen(_START_CMD, stdout=subprocess.PIPE,
-                                  stderr=subprocess.PIPE)
-    try:
-        env_lines = subprocess.check_output(
-            _ENV_INIT_CMD).strip().split('\n')
-        dataset, = [line.split(_DATASET_PREFIX, 1)[1] for line in env_lines
-                    if line.startswith(_DATASET_PREFIX)]
-        host, = [line.split(_HOST_LINE_PREFIX, 1)[1] for line in env_lines
-                 if line.startswith(_HOST_LINE_PREFIX)]
-        # Set environment variables before running the system tests.
-        os.environ[GCD_DATASET] = dataset
-        os.environ[GCD_HOST] = host
-        os.environ['GCLOUD_NO_PRINT'] = 'true'
-        run_module_tests('datastore',
-                         ignore_requirements=True)
-    finally:
-        # NOTE: This is mostly defensive. Since ``proc_start`` will be spawned
-        #       by this current process, it should be killed when this process
-        #       exits whether or not we kill it.
-        proc_start.kill()
-
-
-if __name__ == '__main__':
-    main()
diff --git a/scripts/run_emulator.py b/scripts/run_emulator.py
new file mode 100644
index 000000000000..8ebd809841c6
--- /dev/null
+++ b/scripts/run_emulator.py
@@ -0,0 +1,116 @@
+# Copyright 2016 Google Inc. 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.
+
+"""Run system tests locally with the emulator.
+
+First makes system calls to spawn the emulator and get the local environment
+variable needed for it. Then calls the system tests.
+"""
+
+
+import argparse
+import os
+import subprocess
+
+from gcloud.environment_vars import GCD_DATASET
+from gcloud.environment_vars import GCD_HOST
+from gcloud.environment_vars import PUBSUB_EMULATOR
+from system_tests.run_system_test import run_module_tests
+
+
+PACKAGE_INFO = {
+    'datastore': (GCD_DATASET, GCD_HOST),
+    'pubsub': (PUBSUB_EMULATOR,)
+}
+
+
+def get_parser():
+    """Get simple ``argparse`` parser to determine package.
+
+    :rtype: :class:`argparse.ArgumentParser`
+    :returns: The parser for this script.
+    """
+    parser = argparse.ArgumentParser(
+        description='Run GCloud system tests against local emulator.')
+    parser.add_argument('--package', dest='package',
+                        choices=('datastore', 'pubsub'),
+                        default='datastore', help='Package to be tested.')
+    return parser
+
+
+def get_start_command(package):
+    """Get command line arguments for starting emulator.
+
+    :type package: str
+    :param package: The package to start an emulator for.
+
+    :rtype: tuple
+    :returns: The arguments to be used, in a tuple.
+    """
+    return ('gcloud', 'beta', 'emulators', package, 'start')
+
+
+def get_env_init_command(package):
+    """Get command line arguments for getting emulator env. info.
+
+    :type package: str
+    :param package: The package to get environment info for.
+
+    :rtype: tuple
+    :returns: The arguments to be used, in a tuple.
+    """
+    return ('gcloud', 'beta', 'emulators', package, 'env-init')
+
+
+def run_tests_in_emulator(package):
+    """Spawn an emulator instance and run the system tests.
+
+    :type package: str
+    :param package: The package to run system tests against.
+    """
+    # Make sure this package has environment vars to replace.
+    env_vars = PACKAGE_INFO[package]
+
+    start_command = get_start_command(package)
+    # Ignore stdin and stdout, don't pollute the user's output with them.
+    proc_start = subprocess.Popen(start_command, stdout=subprocess.PIPE,
+                                  stderr=subprocess.PIPE)
+    try:
+        env_init_command = get_env_init_command(package)
+        env_lines = subprocess.check_output(
+            env_init_command).strip().split('\n')
+        # Set environment variables before running the system tests.
+        for env_var in env_vars:
+            line_prefix = 'export ' + env_var + '='
+            value, = [line.split(line_prefix, 1)[1] for line in env_lines
+                      if line.startswith(line_prefix)]
+            os.environ[env_var] = value
+        run_module_tests(package,
+                         ignore_requirements=True)
+    finally:
+        # NOTE: This is mostly defensive. Since ``proc_start`` will be spawned
+        #       by this current process, it should be killed when this process
+        #       exits whether or not we kill it.
+        proc_start.kill()
+
+
+def main():
+    """Main method to run this script."""
+    parser = get_parser()
+    args = parser.parse_args()
+    run_tests_in_emulator(args.package)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tox.ini b/tox.ini
index fb5492590273..74896ec1fd1b 100644
--- a/tox.ini
+++ b/tox.ini
@@ -94,4 +94,14 @@ passenv = {[testenv:system-tests]passenv}
 basepython =
     python2.7
 commands =
-    python {toxinidir}/scripts/datastore_emulator.py
+    python {toxinidir}/scripts/run_emulator.py --package=datastore
+setenv =
+    PYTHONPATH = {toxinidir}/_testing
+    GCLOUD_NO_PRINT=true
+
+[testenv:pubsub-emulator]
+basepython =
+    python2.7
+commands =
+    python {toxinidir}/scripts/run_emulator.py --package=pubsub
+passenv = GCLOUD_*