diff --git a/.cspell.yml b/.cspell.yml
index 4af5060..26ff0f4 100644
--- a/.cspell.yml
+++ b/.cspell.yml
@@ -51,3 +51,8 @@ words:
 
   # Used in Wiki Reporting page, "emacs" file.
   - defun
+
+  # Used in CONTRIBUTING.
+  - maxlevel
+  - replacer
+  - Shellcheck
diff --git a/.github/pull_request_template.md b/.github/pull_request_template.md
new file mode 100644
index 0000000..65c4e94
--- /dev/null
+++ b/.github/pull_request_template.md
@@ -0,0 +1,41 @@
+<!-- Provide a general summary of your changes in the title above. -->
+
+<!--
+IMPORTANT:
+PRs should be small and atomic and should only focus on one thing.
+There should generally only be one commit per PR for changes to the Wiki.
+
+If your PR is making multiple distinct changes, please split it now and submit multiple PRs instead.
+-->
+
+# Description
+<!--
+What do you want to achieve with this PR? What problem does this PR solve?
+Describe your changes in detail and, if relevant, explain which choices you have made and why.
+-->
+
+
+## Related issues/external references
+
+Fixes #
+
+
+## PR checklist
+<!-- Go over all the following points, and put an `x` in all the boxes that apply. -->
+- [ ] I have checked there is no other PR open for the same change.
+- [ ] I have read the [Contribution Guidelines](https://github.com/PHPCSStandards/PHP_CodeSniffer-documentation/blob/main/CONTRIBUTING.md).
+- [ ] I grant the project the right to include my changes under the BSD-3-Clause license (and I have the right to grant these rights).
+- [ ] I have verified that my changes comply with the projects coding standards.
+- [ ] \[When adding a new Wiki page\] I have added the new page to the `_Sidebar.md` file.
+- [ ] \[When adding/updating output examples\] I have verified via the GitHub Actions artifact that the pre-processing handles the command correctly.
+
+<!--
+============================================================================================
+Please make sure your pull request passes all continuous integration checks!
+
+PRs which are failing their CI checks will likely be ignored by the maintainers.
+
+Small PRs using atomic, descriptive commits are hugely appreciated as it will make
+reviewing your changes easier for the maintainers.
+============================================================================================
+-->
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..12696fb
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,146 @@
+# Contributing to the PHP_CodeSniffer Documentation
+
+## Table of Contents
+
+* [PHP_CodeSniffer Wiki](#php_codesniffer-wiki)
+    * [How Does the Wiki Get Updated?](#how-does-the-wiki-get-updated)
+    * [Contributing to the Wiki](#contributing-to-the-wiki)
+    * [Guidelines for Updating the Wiki Files](#guidelines-for-updating-the-wiki-files)
+        * [Running the pre-processing locally](#running-the-pre-processing-locally)
+        * [Running Code Quality Checks Locally](#running-code-quality-checks-locally)
+    * [Frequently Asked Questions](#frequently-asked-questions)
+        * [Why Not Make the Wiki Publicly Editable?](#why-not-make-the-wiki-publicly-editable)
+
+
+## PHP_CodeSniffer Wiki
+
+For now, the documentation for the PHP_CodeSniffer project is available via the [project Wiki](https://github.com/PHPCSStandards/PHP_CodeSniffer/wiki).
+
+### How Does the Wiki Get Updated?
+
+* The source of the Wiki was imported into this repository to maintain the commit history.
+* A [GitHub Actions workflow](https://github.com/PHPCSStandards/PHP_CodeSniffer-documentation/blob/main/.github/workflows/publish-wiki.yml) was added:
+    * It pre-processes the `.md` files to replace placeholders and inject some other content (see [Guidelines for Updating the Wiki Files](#guidelines-for-updating-the-wiki-files)).
+    * And then it pushes the resulting updated `.md` files to the upstream Wiki repo.
+
+<p align="right"><a href="#table-of-contents">back to top</a></p>
+
+
+### Contributing to the Wiki
+
+If you would like to improve the documentation:
+1. Fork this repository.
+2. Create a new branch off the `main` branch.
+3. Make your changes. The Wiki source files are in the `/wiki` subdirectory.
+4. Commit your changes with a meaningful commit message.
+5. Push your changes to your fork.
+6. Submit a pull request from your fork to this repository. This process is documented in more detail in the [GitHub Docs](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request-from-a-fork).
+7. Please ensure your pull requests passes all automated quality checks.
+8. If you updated anything which will be auto-replaced via the pre-processing:
+    * The GitHub Actions workflow will do a "dry-run" for every PR (pre-process only, no push to the Wiki).
+    * Please download the artifact which was created via this dry-run and verify the pre-processing replaced the output in the way you expected.
+
+When in doubt, open an issue first to discuss your change proposal.
+
+<p align="right"><a href="#table-of-contents">back to top</a></p>
+
+
+### Guidelines for Updating the Wiki Files
+
+* Small PRs fixing only one thing will be better received than larger PRs fixing a lot of things in one go.
+* Always use absolute links (https://...). This ensures that the links will work when pages are viewed/edited in this repo, as well as when the pages are viewed from the PHPCS Wiki.
+* Add table of contents placeholders if appropriate.
+    The start of a page containing a table of contents should look like this:
+    ```md
+    ## Table of Contents
+
+    <!-- START doctoc -->
+    <!-- END doctoc -->
+
+    ***
+
+    ... the actual page ...
+    ```
+* Guidelines for command replacement placeholders:
+    * A placeholder MUST look like `{{COMMAND-OUTPUT ...}}` with `...` replaced with a quoted `phpcs` or `phpcbf` command. Example: `{{COMMAND-OUTPUT "phpcbf --report-width=110 --no-colors -h"}}`
+    * A placeholder MUST be at the start of a line.
+    * A placeholder MUST be on a line by itself.
+    * Commands will be run from the project root directory. Keep this in mind when adding a placeholder to a Wiki file.
+* The command replacement will not add markdown code fence syntax, so make sure to do this yourself.
+* If a code sample is needed to generate the desired output, place the code sample in a file in the `build/wiki-code-samples` directory.
+
+<p align="right"><a href="#table-of-contents">back to top</a></p>
+
+
+#### Running the pre-processing locally
+
+As noted above, you don't _need_ to run the pre-processing locally, a dry-run will be done via GitHub Actions for each PR.
+However, if you are making extensive changes, you may still want to test things locally before submitting your PR.
+
+> [!IMPORTANT]
+> Run the bash script first, only run the TOC replacement after.
+
+The bash script used for the command replacements can be run locally from the project root directory by invoking:
+
+```bash
+build/wiki-command-replacer.sh
+```
+
+Notes:
+* For the bash script to succeed, the `phpcs` and `phpcbf` commands need to be available in the `PATH` for your OS.
+* The bash script will copy the Wiki files to the `_wiki` directory before making any replacements to prevent anyone accidentally committing the processed files.
+
+The table of contents generation can be tested locally by installing the `doctoc` tool and running this locally like so:
+
+```bash
+npm install -g doctoc
+doctoc ./_wiki/ --github --maxlevel 4 --update-only
+doctoc ./_wiki/Version-4.0-User-Upgrade-Guide.md --github --maxlevel 3 --update-only
+```
+
+Note that this presumes the command replacer has already run and the files have already been copied to the `_wiki` directory.
+
+If you only want to test the TOC generation, make sure you copy the Wiki files to the `_wiki` directory before running these commands.
+
+<p align="right"><a href="#table-of-contents">back to top</a></p>
+
+
+#### Running Code Quality Checks Locally
+
+All used code quality checks can be run locally.
+Configuration files have been committed to the repository to ensure you will locally get the same results as when the tooling runs in CI.
+
+To run the quality checks locally, install the following tooling:
+* [Yamllint](https://github.com/adrienverge/yamllint)
+    * [Installation instructions](https://yamllint.readthedocs.io/en/stable/quickstart.html)
+    * Run it like so: `yamllint . --format colored --strict --list-files`
+* [Actionlint](https://github.com/rhysd/actionlint)
+    * [Installation instructions](https://github.com/rhysd/actionlint/blob/main/docs/install.md)
+    * Run it like so: `actionlint -verbose`
+* [Markdownlint-cli2](https://github.com/DavidAnson/markdownlint-cli2)
+    * [Installation instructions](https://github.com/DavidAnson/markdownlint-cli2#install)
+    * Run it like so: `markdownlint-cli2`
+* [Lychee](https://github.com/lycheeverse/lychee)
+    * [Installation instructions](https://github.com/lycheeverse/lychee?tab=readme-ov-file#installation)
+    * Run it like so: `lychee "./**/*.md"`
+        Note: this command will show "false positives" locally for the `_Sidebar.md` file. These can be ignored.
+* [CSpell](https://cspell.org/)
+    * [Installation instructions](https://cspell.org/docs/installation)
+    * Run it like so: `cspell "**/*.md"`
+* [Shellcheck](https://www.shellcheck.net/)
+    * [Installation instructions](https://github.com/koalaman/shellcheck?tab=readme-ov-file#installing)
+    * Run it like so: `shellcheck ./build/wiki-command-replacer.sh`
+
+<p align="right"><a href="#table-of-contents">back to top</a></p>
+
+
+### Frequently Asked Questions
+
+#### Why Not Make the Wiki Publicly Editable?
+
+Publicly editable Wiki pages for big projects get vandalized pretty often and we don't want to risk this type of vandalism leading to users getting incorrect information.
+
+As a secondary reason, there are parts of the Wiki (especially the output examples), which were pretty out of date.
+By having the Wiki source in this repository, it allows for automating certain updates which would otherwise have to be done manually.
+
+<p align="right"><a href="#table-of-contents">back to top</a></p>
diff --git a/README.md b/README.md
index 174bbda..38f9f65 100644
--- a/README.md
+++ b/README.md
@@ -8,3 +8,8 @@ The intention is for that website to be a GitHub Pages/Jekyll site, but we'll ne
 In the mean time, the documentation for the PHP_CodeSniffer project is available via the [project Wiki](https://github.com/PHPCSStandards/PHP_CodeSniffer/wiki) and made publicly editable via this repository.
 
 _This is an interim solution and the intention is to eventually migrate the wiki documentation to the website._
+
+
+## Want to contribute ?
+
+Have a look at the [CONTRIBUTING guide](CONTRIBUTING.md).