The Drug Abuse Screening Test (DAST) is a 28-item screening instrument developed by Skinner for clinical screening and treatment evaluation research in the substance abuse field. In a sample of 250 psychiatric patients drawn from four treatment programs, the DAST evidenced high internal consistency reliability and good item-total score correlations. A factor analysis of the DAST item correlation matrix revealed a predominantly unidimensional scale with the possibility of rotating five additional factors reflecting a continuum of drug abuse. The five factors were interpreted as (a) self-recognition of a drug problem, (b) serious social consequences of drug use, (c) help-seeking for drug abuse, (d) illegal drug-related activities, and (e) inability to control drug use. The diagnostic validity of the DAST in discriminating patients according to DSM-III Substance Abuse diagnostic criteria was high and a range of valid clinical DAST cutoff scores from 5/6 through 10/11 was identified. The DAST appears to be a valid measure of drug involvement and abuse in a psychiatric patient population, a finding of increasing clinical relevance.