This Crime and Violence Prevention Field Guide (“Field Guide”) is designed to support USAID officers and other practitioners in the LAC region who are working on citizen security and in other sectors in which crime and violence prevention can be mainstreamed. It provides a conceptual framework for understanding crime, violence, and prevention as part of broader citizen security systems; evidence-based information about effective interventions to prevent crime and violence; and practical advice and tools on how to design, implement, measure, and evaluate crime and violence prevention and citizen security projects. The guide incorporates the research findings of academic and development practitioners in an analysis of crime and violence in the region.