diff --git a/README.md b/README.md
index c653ce8..9e8baf4 100644
--- a/README.md
+++ b/README.md
@@ -288,7 +288,7 @@ mut2 := df.Mutate(
 
 #### Joins
 
-Different Join operations are supported (`InnerJoin`, `LeftJoin`,
+Different Join operations are supported (`InnerJoin`, `OuterJoin`, `LeftJoin`,
 `RightJoin`, `CrossJoin`). In order to use these methods you have to
 specify which are the keys to be used for joining the DataFrames: