Political or social groups wanting to commit mass murder on the basis of racial, ethnic or religious differences are never hindered by a lack of willing executioners. In this book, social psychologist James Waller uncovers the internal and external factors that can lead ordinary people to commit extraordinary acts of evil. Waller debunks the common explanations for genocide--group think, psychopathology, unique cultures--and offers what he believes is a more sophisticated and comprehensive psychological view of how anyone can potentially participate in heinous crimes against humanity. He outlines the evolutionary forces that shape human nature, the individual dispositions that are more likely to engage in acts of evil, and the context of cruelty in which these extraordinary acts can emerge. Illustrative eyewitness accounts are presented at the end of each chapter.