Communities That Care (CTC) is a prevention system, grounded in science that gives communities the tools to address their adolescent health and behavior problems through a focus on empirically identified risk and protective factors. CTC provides a structure for engaging community stakeholders, a process for establishing a shared community vision, tools for assessing levels of risk and protection in communities, and processes for prioritizing risk and protective factors and setting specific, measurable, community goals. CTC guides the coalition to create a strategic community prevention plan designed to address the community’s profile of risk and protection with tested, effective programs and to implement the chosen programs with fidelity. CTC instructs the coalition to monitor program implementation and to periodically reevaluate community levels of risk and protection and outcomes, and to make adjustments in prevention programming if indicated by the data. Implementation of CTC is organized into five stages, each with its own series of “benchmarks” and “milestones” to help guide and monitor implementation progress. CTC is installed in communities through a series of six training events delivered over the course of 6 to 12 months by certified CTC trainers.