The main purpose of this study was to assess treatment change at both the group level and the individual level with a sample of 313 adult male sex offenders. Generally, the results from the group-level analyses were more positive than those from the individual-level analyses. The group-level analyses revealed significant change of medium magnitude on most of the measures, whereas the individual-level analyses indicated more modest gains, with approximately one third of participants showing reliable change and reaching functional levels posttreatment. When representative norms are available, clinical significance provides a clear and established method not only for assessing the effectiveness of sex offender treatment programs but also for evaluating the progress of individual clients.(Published Abstract)