The group of endotrivial modules for the symmetric and alternating groups. Jon F. Carlson, David J. Hemmer, and Nadia Mazza Abstract. We complete a classification of the groups of endotrivial modules for the modular group algebras of symmetric groups and alternating groups. This completes the work begun earlier by Carlson, Mazza and Nakano. Status: to appear in the Proc. Edinburgh Math. Soc.