Official parole supervision files provided details of each criminal's behavior during his supervised release. The PCL made a significant contribution to the prediction of outcome beyond that made several key criminal-history and demographic varibles. The percentage of criminals with low, medium, and high PCL scores who violated the condition of release was 23.5, 48.9, and 65.2, respectively. The probability of remaining out of prison for at least 1 year was .80, .54, and .38 for low, medium, and high groups, respectively. The high group members received more suspensions and presented more supervisory problems than did those in other groups. The results provide support for the validity of the PCL and for the view that it is possible to make useful predictions about some aspects of the criminal psychopath's behavior. (Publisher abstract)