Depending on the subject of the evaluation different outcome measures are necessary. Generally recidivism rates are considered to be state of the art in the assessment of forensic therapy effectiveness. In this context, recidivism can be defined differently. Thus a definition may include only new convictions for a specific type of offense or any offense or may even include new charges as well. In the evaluation of sex offender treatments it is often considered to be self-evident to define recidivism as a reconviction or new charge for a sex offense. Some authors however argue - not without reason - to include any type of violent offense in the definition. The evaluation of treatment effectiveness suggests however, also including therapeutic criteria such as level of openness of the patient. Especially openness about sexual fantasies relevant to the sex offense may be a key factor in the treatment of sex offenders. It is suggested that future research in the area include such ‘softer’ criteria as well.