This Research Brief provides an updated synthesize of current research on effective and promising approaches to the prevention of delinquency and youth diversion from the juvenile justice system. The move away from incarcerating youth to more community-based rehabilitative models requires the funding and implementation of research-based approaches to delinquency prevention and diversion. Prevention is defined in a number of ways, and prevention interventions are designed to address a number of variables. This Research Brief focuses on developmental prevention programs, defined as, "community-based programs designed to prevent antisocial behavior, targeted on children and adolescents, and aiming to change individual, family, or school risk factors." Diversion may involve diverting youth prior to formal charges after initial contact with the police or following a formal charge. The goal of diversion programs is to reduce the likelihood that a youth will recidivate. Diversion has proven more effective than more deep-end involvement (e.g., incarceration) in the juvenile justice system. [For "Making the Right Turn: A Research Update on Improving Transition Outcomes among Youth Involved in the Juvenile Corrections System. Research Brief. Issue 3," see ED585199.]