the effectiveness of adolescent sex offender treatment has received relatively little study when compared to the treatment outcome literature with adult sex offenders. examined even less are the factors associated with treatment success in sexually abusive adolescents. the present study examined recidivism data on 89 youth convicted o f a sexual offense between september 1985 and june 1998. the treatment group consisted of 41 youth who participated in at least 10 months of treatment in the thunder bay adolescent sex offender program (tbasop). included in the comparison group were 23 treatment non-completers (less than 10 months of tbasop) and 25 adolescent sex offenders who did not receive sex offender specific treatment (assessment only group). after an average follow-up period of 7 years, recidivism rates based on subsequent criminal convictions were significantly higher for the treatment non-completers than the treatment completers on measures of nonsexual and serious recidivism. furthermore, while not significant, the treatment completion group sexually re-offended at a lower rate (2.4%) than the treatment non-completers (17.4%) and the assessment only group (4%). these results suggest that adolescent sex offenders commit relatively few sexual re-offenses compared to non-sexual re-offenses but that sex offender specific treatment may be more beneficial in reducing sexual, nonsexual, and serious recidivism.