The collection of papers in this Special Issue came about as a result of the most significant funding award to date dedicated to obtaining a broad perspective of “what works” in the field of policing. In 2009, the National Policing Improvement Agency (NPIA) in the United Kingdom, under the leadership of former Thames Valley Police Chief Constable Peter Neyroud, provided over US$600,000 to the Campbell Collaboration Crime and Justice Group (CCJG), via the Center for Evidence-Based Crime Policy at George Mason University where CCJG’s editorial team is based, to develop a portfolio of systematic reviews on policing topics. In total, 11 systematic searches and reviews were completed and peer reviewed under this program between 2009 and 2013. This Special Issue contains a selection of these reviews not published elsewhere, as well as several papers on lessons learned from the funded projects and areas for future development. The impact of these reviews on the field of policing has been significant. This Special Issue begins with a case study by Telep and Weisburd, which documents the history and development of the CCJG-NPIA systematic review program and its impact on the production of CCJG reviews and evidence-based policing. In addition to more than doubling the number of systematic reviews on policing topics, the program has made a substantial contribution to reversing the historical belief that the police can do nothing to prevent crime. These systematic reviews show us that a number of policing practices and techniques, both existing and innovative, are in fact effective or promising. Three systematic reviews presented in this issue (Gill and colleagues; Higginson and Mazerolle; Meissner and colleagues) suggest that police can have a positive impact not J Exp Criminol (2014) 10:367–369 DOI 10.1007/s11292-014-9218-3