The aim of this meta-analytic study, including 22 studies and 5764 participants, was to examine the effects of aftercare programs on recidivism in juvenile and young adult offenders released from correctional institutions. The studies had to be (quasi-)experimental, with the control group receiving 'care as usual' or no treatment. Recidivism was measured by re-arrests and/or reconvictions and was based on official reports. Although the overall effect size for aftercare programs was generally small (d=.12), moderator analyses indicated more substantial effects and showed that aftercare is most effective if it is well-implemented and consists of individual instead of group treatment, and if it is aimed at older and high-risk youth. Whereas the treatment duration and moment of starting the aftercare program were not related to the program's effectiveness, more intensive aftercare programs were associated with lower recidivism rates. © 2012 Elsevier Ltd.