In this paper we review the contribution of forensic clinical psychology to the investigation, understanding, and formulation of offending behaviour. The most significant contributions have been made in the areas of violence and sexual offending. The forensic clinician will need to be aware of work relating to personality predispositions, of research into the causal role of anger, of the links between mental disorder and offending behaviour, and of the difficulties in determining risk. These are all areas in which significant progress has been made and which are likely to expand and develop in the future.