Aggression is one of the most frequent indications for child and adolescent psychiatric referral, often in association with severe and emergent symptomatology—yet aggression is a normal behavior, present in all people to some extent. The nature, meaning, and prevalence of aggression in children differ as a function of developmental level and context, and it is important to distinguish "pathological," "maladaptive," or "antisocial" manifestations of aggression from "prosocial" or adaptive behaviors (e.g., self-defense). Aggression is generally considered to be a highly stable behavioral trait. Nevertheless, only half of school-age children who are aggressive continue to manifest this behavior in adolescence. When aggression persists, it is highly impairing and often carries severe consequences for academic achievement and occupational attainment, family and peer relationships, and psychological development, as well as risk for dire outcomes—including antisocial personality disorder, substance abuse, and criminality.