Data on the use of OC spray by the Queensland Police Service (QPS) were obtained from crime reports, an officer survey, and complaint files for 2001 and 2002. Additional information from 2003 and 2004 was also examined to determine the longer trend in OC usage rates. Data analysis determined how often and under what circumstances OC spray has been used, whether its use has been appropriate, whether it is an effective use-of-force option, whether it has decreased assaults or injuries, whether it has decreased complaints about police excessive use of force, and whether it is safe. The study found that on average, QPS officers use OC spray two or three times per day. Officers tended to reserve the use of OC spray for high-risk situations, such as when under direct threat of attack or in the process of being assaulted. In a small number of questionable cases, OC spray was used on handcuffed suspects or apparently passive individuals. In 83 percent of the cases examined, the use of OC spray helped officers control a situation; however, it did not have an effect in 10 percent of the cases, and in 1 percent it made the subject's behavior worse. No change was found in the number of assaults on officers since the introduction of OC spray. Complaints about the use of OC spray composed 6 percent of all excessive-force complaints. To date, more than 5,000 people (police officers and subjects) in Queensland have been exposed to the effects of OC spray, with almost no health problems resulting. Recommendations pertain to monitoring OC use, training scenarios, and aftercare. Extensive tables, figures, and 40 references