This book comprises a first-of-its-kind collection of successful applications of problem-oriented policing to a range of policing problems: gang violence; violence against women; vulnerable people; disorderly places; and theft, robbery, and burglary. Written by policing scholars, each of the 23 case studies describes the problem-oriented project, assesses efforts to measure its impact, reports on the longer-term sustainability of the success, and reflects on the broader lessons to be derived from the project. In this introductory chapter, the editors discuss the appropriate standards for “success,” and draw out major themes that cut across the case studies, including how police can shift and share responsibility for addressing problems, counteract resistance from corporate entities whose policies contribute to problems, work productively with researchers on problems, and maintain successes over the longer term.