diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
new file mode 100644
index 0000000..94c292d
--- /dev/null
+++ b/.github/workflows/main.yml
@@ -0,0 +1,21 @@
+name: subtree-index
+
+on: [push]
+
+jobs:
+  sync-downstream:
+
+    runs-on: ubuntu-latest
+
+    name: Update downstream index repo
+
+    steps:
+      - uses: actions/checkout@v2
+        with:
+          fetch-depth: 0
+      - uses: nxtlvlsoftware/git-subtree-action@1
+        with:
+          repo: 'infogulch/index'
+          path: '_notebooks'
+          deploy_key: ${{ secrets.DOWNSTREAM_GITHUB_DEPLOY_KEY }}
+          force: true # will force push to the downstream repository