Problem-oriented policing (POP) has diffused quickly since Herman Goldstein's original conception in 1979. Today, more than two-thirds of large police departments utilize POP. In this project, we conducted a Campbell Collaboration systematic review of POP programs to synthesize the extant literature on problem-oriented policing to determine whether this widely adopted innovation is effective in reducing crime and disorder. Eligible studies for this review had to meet rigorous methodological criteria set forth by Campbell. After an exhaustive literature review, only 10 eligible studies were discovered, which show that in general, POP does help reduce crime, but our ability to contextualize this finding was limited by the small number of methodologically rigorous studies. An examination of pre/post evaluations of problem-oriented policing indicate this program has much promise.