The Psychological Screening Inventory (PSI) was designed for use as a rapid mental health screening device to identify persons who should receive more extensive evaluation. This study evaluated the accuracy of the three screening scales using receiver operating characteristic (ROC), positive predictive power-negative predictive power, and sensitivity-specificity analyses. Persons with major psychiatric disorder (N = 536) were distinguished from control participants by the Alienation scale with an area underneath the ROC curve (AUC) of .905; persons with significant antisocial behavior (N = 410), by the Social Nonconformity (Sn) scale with an AUC of .811; and persons with general psychological distress (N = 620), by the Discomfort (Di) scale with an AUC of .773. There were comparable findings for the other comparison procedures, and some results were better for men and women separately. An empirically developed index (the Overall Screening Index—Revised) showed significant improvement over the Di scale in identifying persons with general psychological distress (AUC = .842). These findings support the utility of the PSI for its intended purpose.