Since the 1990s scholars have focused heavily on the perpetrators of the Holocaust, and have presented a complex and heterogeneous picture of perpetrators. This book provides a unique overview of the current state of research on perpetrators. Contributions approach the topic from various expertise (history, gender, sociology, psychology, law, comparative genocide), and address several unresolved questions. The overall focus is on the key question that it still disputed: How do ordinary people become mass murderers?