Mechanisms controlling aggressive behavior started to be identified from late 20’s of the 20th century and subsequent research described such mechanisms in great detail. While the findings are of great relevance for the understanding of aggression per se, they provide limited insights into the mechanisms of abnormal aggression i.e. those mechanisms that underlie aggression-related psychopathologies. While basic phenomena and mechanism of aggression are presented, this book is the first that comprehensively describes ultimate and proximate mechanisms that transform normal (laboratory animals) or tolerable (humans) manifestations of aggressiveness into abnormal patterns in laboratory animals and aggression-related psychopathologies in humans. This book is written for behavioral neurobiologists and neuroscientists, interested in emotional control in general and aggression research in particular. The book will also offer important information to neurologists and psychiatrists dealing with aggressive behavior in the clinic and ultimately, may provide means to understand and on the long run to discover novel approaches to the treatment of abnormal human aggression.