Forensic assessment is concerned with identifying aspects of an offender’s behaviour that can be rehabilitated or improved by appropriate treatment intervention. This does not mean that forensic assessment is limited to the offender, it can equally be used to examine the state of mind of the victim and witnesses who are likely to be interviewed by the police and to provide evidence in court. Forensic psychologists also use assessments to help devise treatment programmes for offenders. These assessments shed light on the nature of thoughts and feelings held by offenders and whether they have been rehabilitated and are safe to be released into the community. In the case of sex offenders, both the sex offender treatment programme and the sex offender treatment evaluation project have proven to be effective interventions. Accurate assessments are important in the development of relevant and suitably tailored therapies for offenders with different histories of criminal activity and cognitive or emotional or social skills deficits.