Antisocial behavior can be reduced if services focus on changing the known determinants of behavior problems in the natural environments in which children and families live. The development of multisystemic treatment (MST) gives mental health professionals a powerful new tool for confronting antisocial behavior in children and adolescents, especially for children at the extreme end of the continuum, those at risk for out-of-home placement. A broad range of knowledge concerning the social-ecological context of antisocial youth is integrated, and evaluation results are presented. The rationale and methods of MST used to produce lasting change in the serious antisocial behaviors of children and adolescents are presented in the following chapters: (1) "Empirical, Conceptual, and Philosophical Bases of MST"; (2) "Clinical Foundations of MST: Nine Treatment Principles, Home-Based Model of Service Delivery, and Guidelines for Clinical Supervision"; (3) "Assessment of Family Functioning"; (4) "Family Interventions"; (5) "Changing Relations with Peers"; (6) "Promoting Academic and Social Competence in School Settings"; (7) "When and How to Conduct Individually Oriented Interventions"; (8) "Family Linkages with Community Supports"; (9) "Outcomes of MST: Findings from Controlled Evaluations"; and (10) "Policy Implications of the Effectiveness of MST." References and index are appended. (EMK)