Both of these de nitions emphasize behavior that is likely to dramatically enhance the chances of being imprisoned. The epidemiology of antisocial personality disorder (Fazel and Danesh, 2002), based on a summary of over 60 studies, consistently shows that it is more likely to be seen in male than female prisoners, and that 47 percent of male prisoners and 21 percent of female prisoners meet the criteria for this diagnosis. It is clearly the most common mental health diagnosis that prison staff are likely to meet. Treatment, however, is less clear-cut. Fisher and O’Donohue (2006) suggest that contingency management programs (or other reward systems) may be moderately useful for people with antisocial personality disorders. However, this is likely to be more useful for management in a prison setting than as a long-term treatment, even if prison staff have the levels of staf ng and training to deal with antisocial/dissocial personality disorder (which is unlikely in many settings).