diff --git a/.github/.OwlBot.lock.yaml b/.github/.OwlBot.lock.yaml
index 9ee60f7..a9fcd07 100644
--- a/.github/.OwlBot.lock.yaml
+++ b/.github/.OwlBot.lock.yaml
@@ -1,3 +1,3 @@
 docker:
   image: gcr.io/repo-automation-bots/owlbot-python:latest
-  digest: sha256:aea14a583128771ae8aefa364e1652f3c56070168ef31beb203534222d842b8b
+  digest: sha256:9743664022bd63a8084be67f144898314c7ca12f0a03e422ac17c733c129d803
diff --git a/.kokoro/build.sh b/.kokoro/build.sh
index af5c996..cdf0178 100755
--- a/.kokoro/build.sh
+++ b/.kokoro/build.sh
@@ -41,7 +41,7 @@ python3 -m pip install --upgrade --quiet nox
 python3 -m nox --version
 
 # If this is a continuous build, send the test log to the FlakyBot.
-# See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+# See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
 if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"continuous"* ]]; then
   cleanup() {
     chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
diff --git a/.kokoro/test-samples-impl.sh b/.kokoro/test-samples-impl.sh
index 311a8d5..8a324c9 100755
--- a/.kokoro/test-samples-impl.sh
+++ b/.kokoro/test-samples-impl.sh
@@ -80,7 +80,7 @@ for file in samples/**/requirements.txt; do
     EXIT=$?
 
     # If this is a periodic build, send the test log to the FlakyBot.
-    # See https://github.com/googleapis/repo-automation-bots/tree/master/packages/flakybot.
+    # See https://github.com/googleapis/repo-automation-bots/tree/main/packages/flakybot.
     if [[ $KOKORO_BUILD_ARTIFACTS_SUBDIR = *"periodic"* ]]; then
       chmod +x $KOKORO_GFILE_DIR/linux_amd64/flakybot
       $KOKORO_GFILE_DIR/linux_amd64/flakybot
diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5dad1b8..9349e1b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,5 +1,12 @@
 # Changelog
 
+### [0.1.3](https://www.github.com/googleapis/python-source-context/compare/v0.1.2...v0.1.3) (2021-08-23)
+
+
+### Documentation
+
+* Migrate default branch to main ([#17](https://www.github.com/googleapis/python-source-context/issues/17)) ([6011f91](https://www.github.com/googleapis/python-source-context/commit/6011f91031abce8a71c5b6891a1ee8e241d580e0))
+
 ### [0.1.2](https://www.github.com/googleapis/python-source-context/compare/v0.1.1...v0.1.2) (2021-07-29)
 
 
diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 0a16402..b0936ab 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -50,9 +50,9 @@ You'll have to create a development environment using a Git checkout:
    # Configure remotes such that you can pull changes from the googleapis/python-source-context
    # repository into your local repository.
    $ git remote add upstream git@github.com:googleapis/python-source-context.git
-   # fetch and merge changes from upstream into master
+   # fetch and merge changes from upstream into main
    $ git fetch upstream
-   $ git merge upstream/master
+   $ git merge upstream/main
 
 Now your local repo is set up such that you will push changes to your GitHub
 repo, from which you can submit a pull request.
@@ -110,12 +110,12 @@ Coding Style
   variables::
 
    export GOOGLE_CLOUD_TESTING_REMOTE="upstream"
-   export GOOGLE_CLOUD_TESTING_BRANCH="master"
+   export GOOGLE_CLOUD_TESTING_BRANCH="main"
 
   By doing this, you are specifying the location of the most up-to-date
   version of ``python-source-context``. The the suggested remote name ``upstream``
   should point to the official ``googleapis`` checkout and the
-  the branch should be the main branch on that remote (``master``).
+  the branch should be the main branch on that remote (``main``).
 
 - This repository contains configuration for the
   `pre-commit <https://pre-commit.com/>`__ tool, which automates checking
@@ -209,7 +209,7 @@ The `description on PyPI`_ for the project comes directly from the
 ``README``. Due to the reStructuredText (``rst``) parser used by
 PyPI, relative links which will work on GitHub (e.g. ``CONTRIBUTING.rst``
 instead of
-``https://github.com/googleapis/python-source-context/blob/master/CONTRIBUTING.rst``)
+``https://github.com/googleapis/python-source-context/blob/main/CONTRIBUTING.rst``)
 may cause problems creating links or rendering the description.
 
 .. _description on PyPI: https://pypi.org/project/google-cloud-source-context
@@ -234,7 +234,7 @@ We support:
 
 Supported versions can be found in our ``noxfile.py`` `config`_.
 
-.. _config: https://github.com/googleapis/python-source-context/blob/master/noxfile.py
+.. _config: https://github.com/googleapis/python-source-context/blob/main/noxfile.py
 
 
 We also explicitly decided to support Python 3 beginning with version 3.6.
diff --git a/docs/conf.py b/docs/conf.py
index ba999ac..dad92cf 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -76,8 +76,8 @@
 # The encoding of source files.
 # source_encoding = 'utf-8-sig'
 
-# The master toctree document.
-master_doc = "index"
+# The root toctree document.
+root_doc = "index"
 
 # General information about the project.
 project = "google-cloud-source-context"
@@ -110,6 +110,7 @@
 # directories to ignore when looking for source files.
 exclude_patterns = [
     "_build",
+    "**/.nox/**/*",
     "samples/AUTHORING_GUIDE.md",
     "samples/CONTRIBUTING.md",
     "samples/snippets/README.rst",
@@ -279,7 +280,7 @@
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
     (
-        master_doc,
+        root_doc,
         "google-cloud-source-context.tex",
         "google-cloud-source-context Documentation",
         author,
@@ -314,7 +315,7 @@
 # (source start file, name, description, authors, manual section).
 man_pages = [
     (
-        master_doc,
+        root_doc,
         "google-cloud-source-context",
         "google-cloud-source-context Documentation",
         [author],
@@ -333,7 +334,7 @@
 #  dir menu entry, description, category)
 texinfo_documents = [
     (
-        master_doc,
+        root_doc,
         "google-cloud-source-context",
         "google-cloud-source-context Documentation",
         author,
diff --git a/noxfile.py b/noxfile.py
index d896e7f..935a924 100644
--- a/noxfile.py
+++ b/noxfile.py
@@ -84,9 +84,15 @@ def default(session):
     constraints_path = str(
         CURRENT_DIRECTORY / "testing" / f"constraints-{session.python}.txt"
     )
-    session.install("asyncmock", "pytest-asyncio", "-c", constraints_path)
-
-    session.install("mock", "pytest", "pytest-cov", "-c", constraints_path)
+    session.install(
+        "mock",
+        "asyncmock",
+        "pytest",
+        "pytest-cov",
+        "pytest-asyncio",
+        "-c",
+        constraints_path,
+    )
 
     session.install("-e", ".", "-c", constraints_path)
 
diff --git a/owlbot.py b/owlbot.py
index 8950fdd..b2be9c9 100644
--- a/owlbot.py
+++ b/owlbot.py
@@ -31,7 +31,61 @@
 # ----------------------------------------------------------------------------
 
 templated_files = gcp.CommonTemplates().py_library(microgenerator=True)
+python.py_samples(skip_readmes=True)
 s.move(templated_files, excludes=[".coveragerc"]) # the microgenerator has a good coveragerc file
+# Remove the replacements below once https://github.com/googleapis/synthtool/pull/1188 is merged
+
+# Update googleapis/repo-automation-bots repo to main in .kokoro/*.sh files
+s.replace(".kokoro/*.sh", "repo-automation-bots/tree/master", "repo-automation-bots/tree/main")
+
+# Customize CONTRIBUTING.rst to replace master with main
+s.replace(
+    "CONTRIBUTING.rst",
+    "fetch and merge changes from upstream into master",
+    "fetch and merge changes from upstream into main",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "git merge upstream/master",
+    "git merge upstream/main",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    """export GOOGLE_CLOUD_TESTING_BRANCH=\"master\"""",
+    """export GOOGLE_CLOUD_TESTING_BRANCH=\"main\"""",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "remote \(``master``\)",
+    "remote (``main``)",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "blob/master/CONTRIBUTING.rst",
+    "blob/main/CONTRIBUTING.rst",
+)
+
+s.replace(
+    "CONTRIBUTING.rst",
+    "blob/master/noxfile.py",
+    "blob/main/noxfile.py",
+)
+
+s.replace(
+    "docs/conf.py",
+    "master_doc",
+    "root_doc",
+)
+
+s.replace(
+    "docs/conf.py",
+    "# The master toctree document.",
+    "# The root toctree document.",
+)
 
 # ----------------------------------------------------------------------------
 # Run blacken session
diff --git a/scripts/readme-gen/templates/install_deps.tmpl.rst b/scripts/readme-gen/templates/install_deps.tmpl.rst
index a0406db..275d649 100644
--- a/scripts/readme-gen/templates/install_deps.tmpl.rst
+++ b/scripts/readme-gen/templates/install_deps.tmpl.rst
@@ -12,7 +12,7 @@ Install Dependencies
    .. _Python Development Environment Setup Guide:
        https://cloud.google.com/python/setup
 
-#. Create a virtualenv. Samples are compatible with Python 2.7 and 3.4+.
+#. Create a virtualenv. Samples are compatible with Python 3.6+.
 
     .. code-block:: bash
 
diff --git a/setup.py b/setup.py
index a1d7166..d6bc861 100644
--- a/setup.py
+++ b/setup.py
@@ -22,7 +22,7 @@
 
 name = "google-cloud-source-context"
 description = "Python client for Source Context"
-version = "0.1.2"
+version = "0.1.3"
 release_status = "Development Status :: 4 - Beta"
 url = "https://github.com/googleapis/python-source-context"
 dependencies = [