This Field Guide is intended to support USAID Democracy and Governance Officers as they consider police assistance programs in developing countries. The guide establishes the importance of public safety as a cornerstone of successful development. The Inter-agency environment and identification of risk and risk management is presented. A short background section traces the development of various policing styles including community-based and information-driven. The link between pervasive operational problems in developing world policing such as corruption, excessive use of force and poor criminal investigations and back office or "substructure" dysfunction is clearly identified. The importance of connecting leadership to change management as part of police reform is discussed as a logical means to achieve long-term, successful police reform. Multi-disciplinary methods to address crime and security problems including prevention/intervention/enforcement framework are recommended. "Program checkpoints" are included as a guide to project development. "Important Characteristics, Typical Findings and Programming Notes" are presented for all of the major functions in a modern police agency.