The impact of sexual violence is far-reaching, for the victims, the offenders, and the families of both. Thus, the effective treatment of sexual offenders is one of the key objectives of the criminal justice system. Effective treatment will ensure the prevention of future victims and can help the offenders move forward to meaningful lives in which no one else is harmed. This highlights the need to conduct quality treatment outcome research. Treatment effectiveness research commonly involves comparing the recidivism rates of those who received treatment to those who did not. As noted in this entry, the details of these comparisons require careful attention. A number of methodological considerations in conducting treatment outcome research are outlined along with discussion of the pros and cons of various ...