In this systematic review, the effectiveness of psychological treatment interventions for child molesters was examined. Studies were restricted to randomized control trials (RCTs), controlled trials, and cohort designs where recidivism had been used as the outcome variable. ASSIA, NCJRS, Medline, PsychINFO, EMBASE, Pro-requests Dissertations and Theses A&I, and the Cochrane Library were searched. Ten experts were contacted and the reference lists of 12 systematic reviews and 40 primary studies were observed. The number of hits was 3,019, of which 564 duplicates, 2,388 irrelevant references, and 38 that did not meet the inclusion criteria were removed. Fourteen studies using mixed samples had to be omitted because it was not possible to determine the recidivism rates of child molesters in the samples described. One RCT and 9 cohort studies were included in the data synthesis, providing 2,119 participants. In all, 52.1% received the intervention under investigation and 47.9% did not. The reported recidivism rates were 13.9% for the treated child molesters compared to 18.6% for the untreated child molesters. Three studies reported statistically significant lower recidivism rates for treated child molesters. Eight studies were assessed as weak. Four studies were assessed as having bias which increased the chance of finding a treatment effect and four studies were assessed as having bias which reduced the chance of finding a treatment effect. It was not possible to determine the direction of bias for two studies.