Aggression may be defined as: 1) The act of initiating hostilities or invasion; 2) The practice or habit of launching attacks; or 3) The practice or habit of launching attacks. Aggression is one of the most important and most controversial kinds of motivation. Its use as a category in the psychology of motivation has often been criticised, because it is clear that it encompasses a vast range of phenomena, from modern war to squabbles between individuals. There is an important familial component to aggression, antisocial behaviour, crime, and violence. Essentially all people are in some way affected by aggression, whether they are targets of it, engage in it themselves, or are charged with observing and controlling it in others. Thus aggression is of concern to victims, perpetrators, and those professionals charged with its treatment because of personal safety, well-being, or obligation. This new book examines the foundations and manifestations of aggression.