Approximately one in five youth experience a mental health disorder (President’s New Freedom Commission on Mental Health, 2003). In turn, mental health disorders are associated with a host of problems in other domains (e.g., academic and social adjustment difficulties), the combination of which can compromise optimal development (Suldo, Gormley, DuPaul, & Anderson-Butcher, 2014; van Lier et al., 2012). As detailed throughout this book, multiple evidence-based treatment and prevention approaches have been identified that can buffer deleterious effects of mental health disorders and their comorbid challenges. However, despite recent increases in service use for mental disorders among youth (Perou et al., 2013), the majority of youth do not receive mental health services (Merikangas et al., 2011). Moreover, there are significant disparities in mental health access and quality; racial/ethnic minority and low socioeconomic status (SES) youth, as well as uninsured youth, receive treatment at particularly low rates (Merikangas et al., 2011). Given the current landscape of youth mental health issues in the United States, schools are increasingly being called upon to play integral roles in the identification of mental health concerns and provision of mental health services. In this Introduction, we briefly consider schools’ role in light of a social-ecological framework and provide an overview of topics covered in subsequent chapters.