diff --git a/.github/workflows/ci.yaml b/.github/workflows/ci.yaml
new file mode 100644
index 00000000..7b9c6b5d
--- /dev/null
+++ b/.github/workflows/ci.yaml
@@ -0,0 +1,117 @@
+name: CI
+
+on:
+  push:
+    branches: [ master ]
+  pull_request:
+    branches: [ master ]
+
+jobs:
+  lint:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 5
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: actions/setup-python@v2
+      with:
+        python-version: '3.8'
+
+    - uses: actions/cache@v2
+      with:
+        path: ~/.cache/pip
+        key:
+          ${{ runner.os }}-pip-lint-${{ hashFiles('pyproject.toml', 'setup.py', 'tox.ini') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-lint-
+          ${{ runner.os }}-pip-
+
+    - run: python -m pip install tox
+
+    - run: tox -q -p all -e flake8,towncrier,twine,check-manifest
+
+  docs:
+    runs-on: ubuntu-20.04
+    timeout-minutes: 5
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: actions/setup-python@v2
+      with:
+        python-version: "3.8"
+
+    - uses: actions/cache@v2
+      with:
+        path: ~/.cache/pip
+        key:
+          ${{ runner.os }}-pip-docs-${{ hashFiles('pyproject.toml', 'setup.py', 'tox.ini') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-docs-
+          ${{ runner.os }}-pip-
+
+    - run: python -m pip install tox
+
+    - run: tox -q -e docs
+
+
+  test:
+    name: "Test ${{ matrix.python-version }} with ${{ matrix.twisted-version }} Twisted"
+    runs-on: ubuntu-20.04
+    timeout-minutes: 10
+    continue-on-error: ${{ matrix.experimental }}
+    strategy:
+      matrix:
+          python-version: ["2.7", "3.5", "3.6", "3.7", "3.8", "pypy-2.7", "pypy-3.7"]
+          twisted-version: ["lowest", "latest"]
+          experimental: [false]
+
+          include:
+          - python-version: "3.8"
+            twisted-version: "trunk"
+            experimental: true
+
+    steps:
+    - uses: actions/checkout@v2
+
+    - uses: actions/setup-python@v2
+      with:
+        python-version: ${{ matrix.python-version }}
+
+    - uses: actions/cache@v2
+      with:
+        path: ~/.cache/pip
+        key:
+          ${{ runner.os }}-pip-${{ matrix.python-version }}-${{ hashFiles('pyproject.toml', 'setup.py', 'tox.ini') }}
+        restore-keys: |
+          ${{ runner.os }}-pip-${{ matrix.python-version }}-
+          ${{ runner.os }}-pip-
+
+    - name: Translate Python version to Tox factor
+      id: pyfactor
+      shell: python
+      run: |
+        table = {
+          "2.7": "py27",
+          "3.5": "py35",
+          "3.6": "py36",
+          "3.7": "py37",
+          "3.8": "py38",
+          "3.9": "py39",
+          "pypy-2.7": "pypy",
+          "pypy-3.7": "pypy3",
+        }
+        factor = table["${{ matrix.python-version }}"]
+        print("::set-output name=value::" + factor)
+
+    - run: python -m pip install tox coveralls
+
+    - run: tox -e ${{ steps.pyfactor.outputs.value }}-twisted_${{ matrix.twisted-version }}
+
+    - run: coveralls
+      env:
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        COVERALLS_REPO_TOKEN: 4nctuKHTnVtbdmty2FgdO3iiWm1nb7xc4
+        COVERALLS_FLAG_NAME: python_${{ matrix.python-version }}-twisted_${{ matrix.twisted-version }}
+        COVERALLS_PARALLEL: true
diff --git a/.travis.yml b/.travis.yml
deleted file mode 100644
index ecbc6b40..00000000
--- a/.travis.yml
+++ /dev/null
@@ -1,78 +0,0 @@
-# AUTO-GENERATED BY tox2travis.py -- DO NOT EDIT THIS FILE BY HAND!
-
-dist: xenial
-language: python
-
-cache: pip
-
-jobs:
-  include:
-    - python: "3.8"
-      env: TOXENV=towncrier,twine,check-manifest,flake8,docs
-    - python: "2.7"
-      env: TOXENV=py27-twisted_lowest,py27-twisted_latest
-    - python: "3.5"
-      env: TOXENV=py35-twisted_lowest,py35-twisted_latest
-    - python: "3.6"
-      env: TOXENV=py36-twisted_lowest,py36-twisted_latest
-    - python: "3.7"
-      env: TOXENV=py37-twisted_lowest,py37-twisted_latest
-    - python: "3.8"
-      env: TOXENV=py38-twisted_latest
-    - python: "pypy"
-      env: TOXENV=pypy-twisted_lowest,pypy-twisted_latest
-    - python: "pypy3"
-      env: TOXENV=pypy3-twisted_latest
-    - python: "pypy3"
-      env: TOXENV=pypy3-twisted_trunk-pyopenssl_trunk
-      if: branch = master
-    - python: "3.5"
-      env: TOXENV=py35-twisted_trunk-pyopenssl_trunk
-      if: branch = master
-    - python: "3.6"
-      env: TOXENV=py36-twisted_trunk-pyopenssl_trunk
-      if: branch = master
-    - python: "3.7"
-      env: TOXENV=py37-twisted_trunk-pyopenssl_trunk
-      if: branch = master
-    - python: "3.8"
-      env: TOXENV=py38-twisted_trunk-pyopenssl_trunk
-      if: branch = master
-
-  # Don't fail on trunk versions.
-  allow_failures:
-    - env: TOXENV=pypy3-twisted_trunk-pyopenssl_trunk
-    - env: TOXENV=py35-twisted_trunk-pyopenssl_trunk
-    - env: TOXENV=py36-twisted_trunk-pyopenssl_trunk
-    - env: TOXENV=py37-twisted_trunk-pyopenssl_trunk
-    - env: TOXENV=py38-twisted_trunk-pyopenssl_trunk
-
-before_install:
-  - pip install --upgrade pip
-  - pip install --upgrade setuptools
-
-install:
-  - pip install tox coveralls
-
-script:
-  - tox
-
-after_success:
-  - coveralls
-
-after_failure:
-  - |
-    if [[ -f "_trial_temp/httpbin-server-error.log" ]]
-    then
-        echo "httpbin-server-error.log:"
-        cat "_trial_temp/httpbin-server-error.log"
-    fi
-
-notifications:
-  email: false
-
-branches:
-  only:
-    - master
-
-# AUTO-GENERATED BY tox2travis.py -- DO NOT EDIT THIS FILE BY HAND!
diff --git a/changelog.d/307.removal.rst b/changelog.d/307.removal.rst
new file mode 100644
index 00000000..b82c7bfb
--- /dev/null
+++ b/changelog.d/307.removal.rst
@@ -0,0 +1 @@
+The minimum supported Twisted version has increased to 18.7.0. Older versions are no longer tested in CI.
diff --git a/setup.py b/setup.py
index 473ed2fb..6d5e24de 100644
--- a/setup.py
+++ b/setup.py
@@ -33,8 +33,7 @@
             "requests >= 2.1.0",
             "hyperlink >= 19.0.0",
             "six >= 1.13.0",
-            "Twisted[tls] >= 16.4.0 ; python_version < '3.7'",
-            "Twisted[tls] >= 18.7.0 ; python_version >= '3.7'",
+            "Twisted[tls] >= 18.7.0",
             "attrs",
         ],
         extras_require={
diff --git a/src/treq/test/local_httpbin/child.py b/src/treq/test/local_httpbin/child.py
index 5b972b49..dcd1f797 100644
--- a/src/treq/test/local_httpbin/child.py
+++ b/src/treq/test/local_httpbin/child.py
@@ -35,7 +35,7 @@
 from .shared import _HTTPBinDescription
 
 
-def _certificates_for_authority_and_server(service_identity, key_size=1024):
+def _certificates_for_authority_and_server(service_identity, key_size=2048):
     """
     Create a self-signed CA certificate and server certificate signed
     by the CA.
@@ -44,8 +44,8 @@ def _certificates_for_authority_and_server(service_identity, key_size=1024):
     :type service_identity: :py:class:`unicode`
 
     :param key_size: (optional) The size of CA's and server's private
-        RSA keys.  Defaults to 1024 bits, which is the minimum allowed
-        by OpenSSL Contexts at the default security level as of 1.1.
+        RSA keys.  Defaults to 2048 bits, which is the minimum allowed
+        by OpenSSL Contexts at the default security level.
     :type key_size: :py:class:`int`
 
     :return: a 3-tuple of ``(certificate_authority_certificate,
diff --git a/tox.ini b/tox.ini
index 942321d2..663a262c 100644
--- a/tox.ini
+++ b/tox.ini
@@ -2,7 +2,7 @@
 envlist =
     {pypy,py27,py35,py36,py37}-twisted_lowest,
     {pypy,pypy3,py27,py35,py36,py37,py38}-twisted_latest,
-    {pypy3,py35,py36,py37,py38}-twisted_trunk-pyopenssl_trunk,
+    {pypy3,py35,py36,py37,py38}-twisted_trunk,
     towncrier, twine, check-manifest, flake8, docs
 
 [testenv]
@@ -11,13 +11,10 @@ deps =
     coverage
     mock
 
-    !py37-twisted_lowest: Twisted==16.4.0
-    py37-twisted_lowest: Twisted==18.7.0
+    twisted_lowest: Twisted==18.7.0
     twisted_latest: Twisted
     twisted_trunk: https://github.com/twisted/twisted/archive/trunk.zip
 
-    pyopenssl_trunk: https://github.com/pyca/pyopenssl/archive/master.zip
-
     docs: Sphinx>=1.4.8
 setenv =
     # Avoid unnecessary network access when creating virtualenvs for speed.