diff --git a/engine/swarm/index.md b/engine/swarm/index.md
index 35e17a16b1..d06c92fa04 100644
--- a/engine/swarm/index.md
+++ b/engine/swarm/index.md
@@ -52,6 +52,10 @@ Current versions of Docker include *swarm mode* for natively managing a cluster
 of Docker Engines called a *swarm*. Use the Docker CLI to create a swarm, deploy
 application services to a swarm, and manage swarm behavior.
 
+Docker Swarm mode is built into the Docker Engine. Do not confuse Docker Swarm mode
+with [Docker Classic Swarm](https://github.com/docker/classicswarm){:target="_blank" rel="noopener" class="_"}
+which is no longer actively developed.
+
 ## Feature highlights
 
 * **Cluster management integrated with Docker Engine:** Use the Docker Engine