To effectively engage third parties in crime prevention police need to use a range of compliance-seeking mechanisms. In harnessing the crime control capacity of third parties, police need to consider a range of issues: existing deficits in capacity, competency to act against crime, existing incentives to act, and the costs of co-production. Improving the capabilities of the police to reduce crime problems has been a key aim of problem-oriented policing (POP). Informing POP is an evidence-based approach that requires police to develop and implement appropriate strategies. Relevant to promoting innovative problem-solving is the willingness of police to engage third parties in crime control. Harnessing such capacities is critical to POP. The purpose of this paper is to contribute to the growing body of research concerned with police efforts to harness the crime control capacity of external agencies and groups. The paper begins by examining the theoretical basis of harnessing crime control capacity. Different approaches and techniques are then discussed, as well as factors that impact the success of police efforts to draw third parties into crime control efforts. The paper concludes with the examination of a number of implementation issues that have a direct bearing upon the success of drawing third parties into crime reduction efforts. Figures and references