Meta-analyses were performed on 12 studies of treatment with sexual offenders (N = 1,313). A small, but robust, overall effect size was found for treatment versus comparison conditions (r = .12). The overall recidivism rate for treated sexual offenders was .19 versus .27 for untreated sexual offenders. Treatment effect sizes across studies, however, were heterogeneous. Effect sizes were larger in studies that had higher base rates of recidivism, had follow-up periods longer than 5 years, included outpatients, and involved cognitive-behavioral or hormonal treatments. Cognitive-behavioral (p < .0005) and hormonal treatments (p < .00005) were significantly more effective than behavioral treatments but were not significantly different from each other.