This monograph explores the nature and development of aggression and violence in children and youth, especially as manifested within the school setting. It examines the extent of the problem, typical reactions to aggression and violence within the school, and the impact of these reactions on the behavior of students with emotional/behavior disorders. The development of such behavior in children is attributed to such conditions as observation of aggression, victimization, few positive affective social bonds, and reinforcement of the child's own aggressive behavior. Factors possibly explaining the disappointing results of previous prevention and treatment efforts are also discussed. Four types of violent behavior are identified: (1) situational violence (may be exhibited by approximately 40 percent of the population); (2) relationship violence (25 percent of the population); (3) predatory violence (8 percent); and (4) psychopathological violence (0.5 percent). Guidelines for the prevention and treatment of each of these types of violence is offered, suggesting that interventions that are effective with one type of violence may not be effective with other types. Schools are urged to adopt approaches to deal with the various risk factors related to the different types of violence. (Contains 115 references.) (DB)