The study found that the “pulling levers” strategy was associated with a significant reduction in gun homicides in Stockton. The “pulling levers” approach is a specific application of the principles of problem-oriented policing. In its simplest form, the approach consists of six features. First, a particular crime problem is selected, such as gun homicide. Second, an interagency working group of law enforcement practitioners is convened. Third, research is conducted in order to identify key offenders, groups, and behavior patterns. Fourth, a response to offenders and groups of offenders is developed that uses a varied repertoire of sanctions (“pulling levers”) to stop them from continuing their violent behavior. Fifth, social services and community resources are targeted on offenders and groups. Sixth, there is direct and repeated communication with offenders to make them aware why they are being targeted for special attention. In Stockton, these features of the “pulling levers“ strategy were implemented in Operation Peacekeeper, a project designed to deter violent behavior by chronic gang offenders. It reached out directly to gangs, making it clear that gun violence would no longer be tolerated. When gun violence occurred, a battery of resources was applied by police, probation, and prosecution agencies, as well as social-service and community-based partners, in targeting high-risk, chronic gang members. The key outcome variable in the assessment of the impact of the Peacekeeper intervention was the citywide monthly number of gun homicides in Stockton between January 1, 1990, and December 31, 2005. 2 figures, 3 tables, 19 notes, and 77 references