Scholars and policymakers increasingly call for evidence-based, prevention-oriented, and community-driven approaches to improve public health and reduce youth crime, substance use, and related problems. However, few functional models exist. In Communities that Care, four leading experts on prevention describe one such system to illustrate how communities effectively engage in prevention activities. Communities That Care (CTC) is a coalition-based prevention system implemented successfully in dozens of communities across the world that promotes healthy development and reduces crime rates for youth. Drawing on literature from criminology, community psychology, and prevention science this book describes the conditions and actions necessary for effective community-based prevention. The authors illustrate how effective community-based prevention can be undertaken by describing how the CTC prevention system has been developed, implemented, evaluated, and disseminated across the U.S. and internationally. Communities that Care shares invaluable lessons about the implementation and evaluation of community-level interventions and establishes a set of best practices for anyone seeking to engage in and/or evaluate effective prevention efforts.