diff --git a/dev_requirements.txt b/dev_requirements.txt
new file mode 100644
--- /dev/null
+++ b/dev_requirements.txt
@@ -0,0 +1,6 @@
+pytest>=2.7.0,<3.0
+pytest-runner
+pytest-sugar>=0.7.0,<1.0.0
+webtest==1.4.3
+mock
+sphinx
diff --git a/docs/contributing.rst b/docs/contributing.rst
--- a/docs/contributing.rst
+++ b/docs/contributing.rst
@@ -48,11 +48,15 @@ on Bitbucket_ and create a local clone o
 Running tests
 -------------
 
-After finishing your changes make sure all tests pass cleanly. You can run
-the testsuite by running ``py.test`` from the project root::
+After finishing your changes make sure all tests pass cleanly. Install the test
+dependencies, then run the testsuite by invoking ``py.test`` from the
+project root::
 
+    pip install -r dev_requirements.txt
     py.test
 
+Note that testing on Python 2.6 also requires ``unittest2``.
+
 You can also use ``tox`` to run the tests with all supported Python versions
 (currently Python 2.6--2.7).
 
diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -38,7 +38,6 @@ requirements = [
     "alembic>=0.8.0,<0.9",
     "waitress==0.8.8",
     "webob>=1.0.8,<=1.1.1",
-    "webtest==1.4.3",
     "Pylons>=1.0.0,<=1.0.2",
     "Beaker==1.6.4",
     "WebHelpers==1.3",
@@ -52,24 +51,19 @@ requirements = [
     "python-dateutil>=1.5.0,<2.0.0",
     "markdown==2.2.1",
     "docutils>=0.8.1,<=0.11",
-    "mock",
     "URLObject==2.3.4",
     "Routes==1.13",
-    "pytest>=2.7.0,<3.0",
-    "pytest-sugar>=0.7.0,<1.0.0",
     "dulwich>=0.14.1",
     "mercurial>=2.9,<3.9",
 ]
 
 if sys.version_info < (2, 7):
     requirements.append("importlib==1.0.1")
-    requirements.append("unittest2")
     requirements.append("argparse")
 
 if not is_windows:
     requirements.append("bcrypt>=2.0.0")
 
-
 dependency_links = [
 ]
 
@@ -147,9 +141,7 @@ setup(
     url=__url__,
     install_requires=requirements,
     classifiers=classifiers,
-    setup_requires=['PasteScript>=1.6.3',
-                    'pytest-runner'],
-    tests_require=['pytest'],
+    setup_requires=['PasteScript>=1.6.3'],
     data_files=data_files,
     packages=packages,
     include_package_data=True,
diff --git a/tox.ini b/tox.ini
--- a/tox.ini
+++ b/tox.ini
@@ -6,7 +6,8 @@ envlist = py{26,27}-pytest
 setenv =
     PYTHONHASHSEED = 0
 deps =
-    pytest: pytest
+    -r{toxinidir}/dev_requirements.txt
+    py26-pytest: unittest2
     python-ldap
     python-pam
 commands =