Sponsored by the Adolescent Mental Health Initiative of the Annenberg Public Policy Center (APPC) of the University of Pennsylvania and the Sunnylands Trust, this book provides a major update since the first edition in 2006. It addresses the state of our knowledge about mental health disorders in the teenage years, a developmental period when behavior and the brain are still “plastic.” 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 suicide in sections that define each disorder, outline and assess treatments, discuss prevention strategies, and suggest a research agenda based on what we know and don’t know about these conditions. Two additional behavioral disorders—gambling and Internet addiction—are covered in this edition. As a 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 other relevant issues: the stigma of mental illness and the research, policy, and practice context for the delivery of evidence-based treatments. Integrating the work of 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 policymakers alike about the state of our nation's response to the needs of adolescents with mental disorders.