Forty case histories were drawn from a double-blind antagonist study of the Narcotic Antagonist Work-Release Program of the Nassau County Correctional Center (N.Y.). Each subject was scored on the National Institute of Drug Abuse Psycho-Social Inventory, which assesses general background and work, family criminal, and drug histories. Statistical correlation was sought by category with each subject's objective jail score, which reflected success in the jail program. Results suggest that the rehabilitative potential of an inmate in a work-release program can be predicted on the basis of his work history is found. The study confirmed the general hypothesis that some aspects of past behavior are good predictors of future behavior. Further analysis shows that all components of work history must be considered if prediction accuracy is to be served. The number of months in each job reflects the subject's frustration tolerance and ability to interact with authority figures. The more recent the good work history, the more successful the inmate is likely to be in work-release. Positive recent work history also correlates with a subject's good jail record. Tabular data, a list of five references, and an appendix presenting the study instrument and scoring system are provided.