The activities of a further 3,122 police officers in control locations were monitored to determine the changes by the carrying of CS spray. The police officers in the study group received training prior to receiving the CS spray; most were trained to shout a warning before spraying CS. The analysis revealed that police officers in the experimental areas reported 726 incidents in which CS was drawn and used, 28 in which both a baton and CS were drawn and used, and 381 in which CS was drawn but not used. Findings suggested that an officer carrying CS will draw and use it once every 32 months. The overwhelming majority of incidents in which CS was used were public disorder cases or domestic disputes. Police used CS mainly to defend themselves, a colleague, or a member of the public. CS typically took effect within 5 seconds, but it had no effect in nearly 1 in 10 incidents. Results also revealed little difference between test and control locations in the risk that police officers experienced of sustaining injury requiring hospital attention. Data on assaults on police officers produced mixed results. Results also suggest that CS spray did not cause injuries needing hospital treatment more often for its targets than for police. The police officers interviewed generally felt favorably of the CS incapacitant. Two surveys of the public revealed that 67 percent or more favored the issuing of CS spray to police officers. Tables, reference, and list of other papers form the Police Research Group