While an adolescent sexual offender's response to treatment is thought to be impacted by both static and dynamic factors, there is no objective method of assessing the likelihood of success or failure in treatment. The assessment of amenability to treatment is generally a subjective process completed by clinicians in the field. Using descriptive discriminant analysis, pre and post treatment data collected from a residential sex offender program for adolescent males (N = 138) are examined. Participants were identified as belonging to one of three groups: Adolescent sex offenders entering residential sex offender treatment (n = 56); adolescent sex offenders who have completed residential sex offender treatment (n = 63); and, adolescent sex offenders who entered residential treatment, but failed to complete treatment (n = 19). Two treatment outcome variables assessing the level of offender cognitive distortions and three demographic/background variables (the level of intellectual functioning, history of witnessing domestic violence, and history of personal victimization) were identified as having the strongest potential to discriminate between offenders who completed treatment and those who did not enter or did not complete treatment. Implications of these findings for determining treatment amenability and future research are discussed. (Contains 4 tables.)