diff --git a/doc/source/api.rst b/doc/source/api.rst
index 33577a5badc54..b617009fe2f13 100644
--- a/doc/source/api.rst
+++ b/doc/source/api.rst
@@ -861,6 +861,7 @@ Combining / joining / merging
    :toctree: generated/
 
    DataFrame.append
+   DataFrame.assign
    DataFrame.join
    DataFrame.merge
    DataFrame.update