Journal of Experimental Criminology

, Volume 1, Issue 1, pp 117-146

First online:

The effectiveness of treatment for sexual offenders: A comprehensive meta-analysis

  • Friedrich LöselAffiliated withUniversity of Erlangen
  • , Martin SchmuckerAffiliated withUniversity of ErlangenInstitute of Psychology Email author 

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The article reports a meta-analysis on controlled outcome evaluations of sexual offender treatment. From 2,039 documents published in five languages, 69 studies containing 80 independent comparisons between treated and untreated offenders fulfilled stepwise eligibility criteria (total N = 22,181). Despite a wide range of positive and negative effect sizes, the majority confirmed the benefits of treatment. Treated offenders showed 6 percentage points or 37% less sexual recidivism than controls. Effects for violent and general recidivism were in a similar range. Organic treatments (surgical castration and hormonal medication) showed larger effects than psychosocial interventions. However, this difference was partially confounded with methodological and offender variables. Among psychological programs, cognitive–behavioral approaches revealed the most robust effect. Nonbehavioral treatments did not demonstrate a significant impact. There was no outcome difference between randomized and other designs, however, group equivalence was associated with slightly larger effects. Various other moderators had a stronger impact on effect size (e.g., small sample size, quality of outcome reporting, program completion vs. dropout, age homogeneity, outpatient treatment, and authors’ affiliation with the program). More differentiated, high-quality evaluations are needed to clarify: What works for whom under which circumstances?