There has been an upsurge of new research on the escalation of violence and mass murder in National Socialism in the past two decades, expanding our knowledge of the period tremendously. Explanatory models, terminology, sources, research methods and narrations are numerous and differentiated. The same is true of research on the transmission and discourse of memory and the forms memories of violent crimes in National Socialism can take. There have also been many, albeit less numerous, new studies of other cases of collective violence, for example in Yugoslavia and in Rwanda. The comparative study of processes of collective violence however, including the study of the cultural and psychological consequences of violence, is still in its infancy.