Reviews longitudinal and treatment studies of conduct disorder (CD) and proposes a developmental approach to its prevention. Outcome studies for the treatment of CD and antisocial behavior demonstrate that, although none have been entirely successful, many interventions have powerful effects on various symptoms that comprise the disorder, highly predictive antecedents, and risk factors. The development of CD and the potency and interrelationship among antecedent and mediating variables is traced through the preschool and early elementary school years. Developmental and treatment research findings are synthesized to suggest possible integrations of interventions that are promising for future preventive trials in the preschool and elementary school periods. It is concluded that, multisetting interventions after transition to school are essential.