diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 31a46710..a1181891 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -11,6 +11,8 @@ issue before starting any pull requests.
 ## Pull Requests
 We actively welcome your pull requests.
 
+Note: pull requests are not imported into the GitHub directory in the usual way. There is an internal Meta repository that is the "source of truth" for the project. The GitHub repository is generated *from* the internal Meta repository. So we don't merge GitHub PRs directly to the GitHub repository -- they must first be imported into internal Meta repository. When Meta employees look at the GitHub PR, there is a special button visible only to them that executes that import. The changes are then automatically reflected from internal Meta repository back to GitHub. This is why you won't see your PR having being directly merged, but you still see your changes in the repository once it reflects the imported changes.
+
 1. Fork the repo and create your branch from `main`.
 2. If you've added code that should be tested, add tests.
 3. If you've changed APIs, update the documentation.