Healthy mental, emotional, and behavioral (MEB) development is a critical foundation for a productive adulthood. Much is known about strategies to support families and communities in strengthening the MEB development of children and youth, by promoting healthy development and also by preventing and mitigating disorder, so that young people reach adulthood ready to thrive and contribute to society. Over the last decade, a growing body of research has significantly strengthened understanding of healthy MEB development and the factors that influence it, as well as how it can be fostered. Yet, the United States has not taken full advantage of this growing knowledge base. Ten years later, the nation still is not effectively mitigating risks for poor MEB health outcomes; these risks remain prevalent, and available data show no significant reductions in their prevalence. Fostering Healthy Mental, Emotional, and Behavioral Development in Children and Youth: A National Agenda examines the gap between current research and achievable national goals for the next ten years. This report identifies the complexities of childhood influences and highlights the need for a tailored approach when implementing new policies and practices. This report provides a framework for a cohesive, multidisciplinary national approach to improving MEB health.