diff --git a/.travis.yml b/.travis.yml
index 4cdef8603..c7b014038 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -28,13 +28,6 @@ matrix:
     - python: 3.8
       env: TOXENV=mypy
 
-    - python: 3.5
-      env: TOXENV=coverage-py35-tw184,codecov
-    - python: 3.5
-      env: TOXENV=coverage-py35-tw192,codecov
-    - python: 3.5
-      env: TOXENV=coverage-py35-twcurrent,codecov
-
     - python: 3.6
       env: TOXENV=coverage-py36-tw184,codecov
     - python: 3.6
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 4f25daf9f..8f37e29d6 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -45,7 +45,7 @@ Code
   Klein uses `Twisted Trial <http://twistedmatrix.com/documents/current/api/twisted.trial.html>`_ and `tox <https://tox.readthedocs.io/en/latest/>`_ for its tests.
   The command to run the full test suite is ``tox`` with no arguments.
   This will run tests against several versions of Python and Twisted, which can be time-consuming.
-  To run tests against only one or a few versions, pass a ``-e`` argument with an environment from the envlist in ``tox.ini``: for example, ``tox -e py35-twcurrent`` will run tests with Python 3.5 and the current released version of Twisted.
+  To run tests against only one or a few versions, pass a ``-e`` argument with an environment from the envlist in ``tox.ini``: for example, ``tox -e py38-twcurrent`` will run tests with Python 3.8 and the current released version of Twisted.
   To run only one or a few specific tests in the suite, add a filename or fully-qualified Python path to the end of the test invocation: for example, ``tox klein.test.test_app.KleinTestCase.test_foo`` will run only the ``test_foo()`` method of the ``KleinTestCase`` class in ``klein/test/test_app.py``.
   These two test shortcuts can be combined to give you a quick feedback cycle, but make sure to check on the full test suite from time to time to make sure changes haven't had unexpected side effects.
 - Show us your code changes through pull requests sent to `Klein's GitHub repo <https://github.com/twisted/klein>`_.
diff --git a/pyproject.toml b/pyproject.toml
index 85b5fb44e..23bb815d4 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -7,4 +7,4 @@ build-backend = "setuptools.build_meta"
 [tool.black]
 
 line-length = 80
-target-version = ["py35"]
+target-version = ["py36"]
diff --git a/setup.py b/setup.py
index a4f247165..2e49dbd7a 100644
--- a/setup.py
+++ b/setup.py
@@ -12,7 +12,6 @@
             "License :: OSI Approved :: MIT License",
             "Operating System :: OS Independent",
             "Programming Language :: Python",
-            "Programming Language :: Python :: 3.5",
             "Programming Language :: Python :: 3.6",
             "Programming Language :: Python :: 3.7",
             "Programming Language :: Python :: 3.8",
diff --git a/tox.ini b/tox.ini
index bf568dafa..985e09474 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,7 +2,7 @@
 
 envlist =
     flake8, black, mypy
-    coverage-py{35,36,37,38,39,py3}-tw{184,192,current,trunk}
+    coverage-py{36,37,38,39,py3}-tw{184,192,current,trunk}
     coverage_report
     docs, docs-linkcheck
     packaging
@@ -64,7 +64,6 @@ setenv =
 description = run tests
 
 basepython =
-    py35: python3.5
     py36: python3.6
     py37: python3.7
     py38: python3.8
@@ -378,8 +377,8 @@ ignore_missing_imports = True
 description = generate coverage report
 
 depends =
-    coverage-py{35,36,37,38,39,py3}-tw{1,2}{0,1,2,3,4,5,6,7,8,9}{0,1,2,3,4,5,6,7,8,9}
-    coverage-py{35,36,37,38,39,py3}-tw{current,trunk}
+    coverage-py{36,37,38,39,py3}-tw{1,2}{0,1,2,3,4,5,6,7,8,9}{0,1,2,3,4,5,6,7,8,9}
+    coverage-py{36,37,38,39,py3}-tw{current,trunk}
 
 basepython = {[default]basepython}