diff --git a/README.md b/README.md
new file mode 100644
index 0000000..0376a56
--- /dev/null
+++ b/README.md
@@ -0,0 +1,5 @@
+# Ecal
+A submodule of ldmx-sw focused on digi emulation, reconstruction, event object definition, veto calculation, and other Ecal-related tasks.
+
+This repository cannot be built independent of ldmx-sw. If you wish to develop a branch here, you should clone all of ldmx-sw and then checkout
+your branch from there.