Evidence-based policing (EBP) is using data, analysis, and research to complement experience and professional judgment in order to provide the best possible police service to the public. This publication offers a practical framework to understanding EBP. The framework is presented in 45 small “bytes.” The number is arbitrary, but it illustrates the fact that policing is a broad function in a society that expects a lot from the police. Although it’s mainly written with high-ranking law enforcement officials in mind, many others will find this guidebook’s content beneficial in measuring effective policing. It covers topics such as gauging external and internal conditions, assessing performance, identifying and analyzing problems, and evaluating practices and testing alternatives. The guidebook emphasizes what data, analysis, and research capabilities police agencies should have and explains why those capabilities are important, with examples.