diff --git a/README.md b/README.md
index aa7cc56..7156fae 100644
--- a/README.md
+++ b/README.md
@@ -164,6 +164,7 @@ _412 TILs and counting..._
 - [Default Screenshot Location](mac/default-screenshot-location.md)
 - [Insert A Non-Breaking Space Character](mac/insert-a-non-breaking-space-character.md)
 - [List All The Say Voices](mac/list-all-the-say-voices.md)
+- [Resizing Both Corners Of A Window](mac/resizing-both-corners-of-a-window.md)
 
 ### PostgreSQL
 
diff --git a/mac/resizing-both-corners-of-a-window.md b/mac/resizing-both-corners-of-a-window.md
new file mode 100644
index 0000000..86e1ba9
--- /dev/null
+++ b/mac/resizing-both-corners-of-a-window.md
@@ -0,0 +1,4 @@
+# Resizing Both Corners Of A Window
+
+Hold the `option` key while resizing a corner of a window and it will
+simultaneously and equivalently resize the opposite corner.