Mental health and substance use disorders among children, youth, and young adults are major threats which often carryover into adulthood. The costs of treatment for these disorders, which create an enormous burden on the affected individuals, their families, and society, have stimulated increasing interest in prevention practices that can impede the onset or reduce the severity of the disorders. Prevention practices have emerged in a variety of settings, including programs for selected at-risk populations, school-based interventions, interventions in primary care settings, and community services designed to address a broad array of mental health needs and populations.<BR>Researchers and policy makers in prevention science, mental health, education, substance abuse, juvenile justice, health, and child and youth development will depend on this updated information and suggested directions for the field of mental health and prevention of disorders.