diff --git a/roles/matrix-dendrite/defaults/main.yml b/roles/matrix-dendrite/defaults/main.yml
index e8e307edb..61e5f7100 100644
--- a/roles/matrix-dendrite/defaults/main.yml
+++ b/roles/matrix-dendrite/defaults/main.yml
@@ -114,6 +114,10 @@ matrix_dendrite_trusted_id_servers:
   - "matrix.org"
   - "vector.im"
 
+# Controls whether Dendrite will federate at all.
+# Disable this to completely isolate your server from the rest of the Matrix network.
+matrix_dendrite_disable_federation: false
+
 # Default Dendrite configuration template which covers the generic use case.
 # You can customize it by controlling the various variables inside it.
 #
diff --git a/roles/matrix-dendrite/templates/dendrite/dendrite.yaml.j2 b/roles/matrix-dendrite/templates/dendrite/dendrite.yaml.j2
index f5744dd5b..2559be15a 100644
--- a/roles/matrix-dendrite/templates/dendrite/dendrite.yaml.j2
+++ b/roles/matrix-dendrite/templates/dendrite/dendrite.yaml.j2
@@ -64,7 +64,7 @@ global:
 
   # Disables federation. Dendrite will not be able to make any outbound HTTP requests
   # to other servers and the federation API will not be exposed.
-  disable_federation: false
+  disable_federation: {{ matrix_dendrite_disable_federation|to_json }}
 
   # Configuration for Kafka/Naffka.
   kafka: