Abstract: This study represents an examination of recidivism rates associated with the pilot project of Circles of Support and Accountability (COSA) in South-Central Ontario, Canada. A group of 60 high-risk sexual offenders involved in COSA after having been released at the end of their sentence were matched to a group of 60 high-risk sexual offenders who had been released at the end of their sentence, but who did not become involved in COSA. Results show that the offenders who participated in the COSA pilot project had significantly lower rates of any type of reoffending than did the offenders who did not participate in COSA. Specifically, offenders who participated in COSA had a 70% reduction in sexual recidivism in contrast to the matched comparison group (5%vs. 16.7%), a 57% reduction in all types of violent recidivism (including sexual −15%vs. 35%), and an overall reduction of 35% in all types of recidivism (including violent and sexual – 28.3%vs. 43.4%). Further, a considerable harm reduction function was noted in the COSA sample, in that sexual reoffences in this group were categorically less severe than prior offences by the same individual. This function was not observed in the matched comparison group.