Clinicians and researchers have long recognized that adolescent delinquency, substance use, smoking, and risky sexual behavior tend to co-occur. Until now, however, the field has lacked a thoughtful examination of why this pattern exists and the implications for research, policy, and practice. Filling a crucial gap, this volume provides a comprehensive analysis of current knowledge on the multiproblem phenomenon. Leading interdisciplinary experts draw on clinical and public health perspectives to shed new light on the causes and consequences of adolescent behavior problems/m-/and to examine "what works" in prevention and treatment. Mapping out important future directions for the field, this is a state-of-the-science sourcebook and text for anyone working with or studying adolescents at risk. The volume first reviews the epidemiology of serious youth problems and documents their costs to individuals, families, and communities. A lifespan developmental perspective is brought to bear on understanding risk and protective factors for problem behavior, with consideration of biological, family, school, peer, and community influences.; Building on these foundations, subsequent chapters pres