In the course of this research project, patterns of leftist underground activities and their persecution during Austro-Fascism were studied exemplarily. The object of investigation was the Kommunistischer Jugendverband (Communist Youth Association, KJV) in the Viennese districts of Ottakring and Hernals. Of special interest were the illegal KJV-structures, their social profile and activity patterns, as well as the methods used against them by the authorities.