In this chapter, we review developmental theories related to aggressive behavior. The development of aggression and other forms of antisocial behavior has been a central concern in the field of developmental psychopathology (1), and a large body of research has focused on elucidating the development of these behaviors. As will be evident, however, current developmental models do not always distinguish aggression and other antisocial acts. Whenever possible, this review will focus specifically on aggression, and we will describe one developmental model that explicitly illustrates different pathways to aggression versus other antisocial behaviors. In addition to reviewing prominent theories on the development of aggression, we will also consider social information processing approaches to understanding aggressive behavior, discuss risk factors that cut across developmental models, and outline prevention and treatment efforts as they relate to these models. Although we recognize the importance of genetic and physiologic factors in the development of aggression, consideration of these factors is beyond the scope of the current chapter (see 2, 3 for reviews).