Violence in elementary schools is often the subject of current discussions in the media and politics. In recent years, violent incidents in schools have increased, as demonstrated by the rampage in Erfurt, the events at the Rütli School in Berlin, and at the Herschel School in Nuremberg. This book addresses the theoretical foundations of violence in elementary schools. First, it is important to distinguish between the terms "aggression" and "violence." Following that, the phenomenology of violence is explained, which includes various categorizations, such as those by Galtung, Petermann & Petermann, and Hans Hielscher. Next, the development of violence in schools is discussed. Additionally, a model of risk factors (personality, family, leisure, school, and society) and various theories of aggression, including classical and newer psychological theories, are examined.