diff --git a/Doc/reference/expressions.rst b/Doc/reference/expressions.rst
--- a/Doc/reference/expressions.rst
+++ b/Doc/reference/expressions.rst
@@ -377,8 +377,15 @@
 
 .. index:: object: generator
 
-The following generator's methods can be used to control the execution of a
-generator function:
+
+Generator-iterator methods
+^^^^^^^^^^^^^^^^^^^^^^^^^^
+
+This subsection describes the methods of a generator iterator.  They can
+be used to control the execution of a generator function.
+
+Note that calling any generator method when the generator is already
+executing raises an exception.
 
 .. index:: exception: StopIteration
 
diff --git a/Misc/NEWS b/Misc/NEWS
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -191,6 +191,9 @@
 Documentation
 -------------
 
+- Issue #15355: Document that calling a generator method when the generator
+  is already executing raises an exception. Patch by Chris Jerdonek.
+
 - Issue #15230: Clearly document some of the limitations of the runpy
   module and nudge readers towards importlib when appropriate.