Sponsored by the Adolescent Mental Health Initiative of the Annenberg Public Policy Center (APPC) of the University of Pennsylvania and the Annenberg Foundation Trust at Sunnylands Trust, Treating and Preventing Adolescent Mental Health Disorders, Second Edition, provides a major update since the first edition in 2005. It addresses the current state of knowledge about the major mental health disorders that emerge during adolescence, including updated DSM-5 diagnostic criteria. Here, six commissions established by the APPC and the Sunnylands Trust pool their expertise on adolescent anxiety, schizophrenia, substance use disorders, depression and bipolar disorders, eating disorders, and suicidal behavior in sections that thoroughly define each disorder, outline and assess available treatments, discuss prevention strategies, and suggest a research agenda based on what we know and don’t yet know about these various conditions. Two additional behavioral disorders-gambling and internet addiction–are covered in this second edition.As a meaningful counterpoint to its primary focus on mental illness, the volume also incorporates the latest research from a seventh commission–on positive youth development–which addresses how we can fully prepare young people to be happy and successful throughout their lives. Concluding chapters discuss overarching issues regarding the behavioral and mental health of adolescents: overcoming the stigma of mental illness, the research, policy, and practice context for the delivery of evidence-based treatments, and the development of a more robust agenda to advance adolescent health. Integrating the work of eminent scholars in both psychology and psychiatry, this work will be an essential volume for academics and practicing clinicians and will serve as a wake-up call to mental health professionals and policy makers alike about the state of our nation’s response to the needs of adolescents with mental disorders.