We discuss how the five core competencies for healthy adjustment in adolescence (a positive sense of self, self-control, decision-making skills, a moral system of belief, and prosocial connectedness) are represented in theories of aggression and youth violence. We then discuss research supporting the relation between these core competencies and aggressive and violent behavior in childhood and adolescence. Finally, we address the degree to which these core competencies have been included and systematically evaluated within school-based prevention programs, and we end with suggestions for future directions.