diff --git a/docs/intro.rst b/docs/intro.rst
index e89c9af20..483d7eea5 100644
--- a/docs/intro.rst
+++ b/docs/intro.rst
@@ -88,6 +88,11 @@ However, for the quick and dirty:
 
 Congratulations. You now have a virtual environment all set up.
 
+.. note::
+
+    Scripts executed with ``py -3`` will ignore any currently active virtual
+    environment, as the ``-3`` specifies a global scope.
+
 Basic Concepts
 ---------------