The Premorbid Adjustment Scale (PAS) is a rating scale which was developed to be applicable in a research setting. It is designed to evaluate the degree of achievement of developmental goals at each of several periods of a subject's life before the onset of schizophrenia. A description of the scale and its use is presented, along with a discussion of psychometric properties. The PAS has been found to be useful in identifying patients likely to become chronically hospitalized or at high risk for readmission. It may also serve as a possible predictor of patients with brain abnormalities on a computerized tomography (CT) scan.