diff --git a/.github/workflows/jekyll-build.yml b/.github/workflows/jekyll-build.yml
new file mode 100644
index 0000000..e28ee3a
--- /dev/null
+++ b/.github/workflows/jekyll-build.yml
@@ -0,0 +1,23 @@
+name: Jekyll Build
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v6
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: "3.4.10"
+          bundler-cache: true
+
+      - name: Build site
+        run: bundle exec jekyll build --destination _site
+
diff --git a/README b/README
index 4cf64e3..ad04807 100644
--- a/README
+++ b/README
@@ -1,3 +1,68 @@
 # arks.org
 
-Built with Jekyll.
+This site is built with Jekyll.
+
+## Build environment
+
+The project uses:
+
+- Ruby 3.4.10, selected by `.ruby-version`
+- Bundler 2.6.9, recorded in `Gemfile.lock`
+- Jekyll 4.4.1 or later within the `Gemfile` constraint
+
+## Install Ruby
+
+Install Ruby 3.4.10 using a Ruby version manager, `rbenv` for example.
+From the project directory, run:
+
+```sh
+rbenv install 3.4.10
+rbenv local 3.4.10
+ruby --version
+```
+
+The last command should report Ruby 3.4.10. 
+
+## Install dependencies
+
+Install the Bundler version recorded in the lockfile, then install the locked gems:
+
+```sh
+gem install bundler -v 2.6.9
+bundle --version
+bundle install
+```
+
+Verify the resolved Jekyll version:
+
+```sh
+bundle exec jekyll --version
+```
+
+The current lockfile resolves Jekyll 4.4.1. To intentionally update dependencies after changing `Gemfile`, run:
+
+```sh
+bundle update
+```
+
+## Build the site
+
+Generate the static site in `_site/`:
+
+```sh
+bundle exec jekyll build --destination _site
+```
+
+The `_site/` directory is generated output and should not be edited directly.
+
+## Preview locally
+
+Start a local server with live reload:
+
+```sh
+bundle exec jekyll serve --livereload
+```
+
+Open <http://localhost:4000/arks.github.io/> in a browser.
+
+