In recent years the pace has been accelerating by which changes in the Diagnostic and Statistical Manual of Mental Disorders (DSM) systems are made. Revisions occur before extensive empirical knowledge can be drawn upon to guide these changes. For substance use disorders, the criteria have undergone changes from DSM-III to DSM-III-R, and from DSM-III-R to DSM IV. The extent and impact of these revisions have not been formally investigated in an adolescent population. This study compared the three DSM systems in an adolescent clinical sample with respect to how youth were sorted into alcohol diagnostic groups and in terms of their relative concurrent validity. Adolescents (N=130) receiving drug abuse assessments at an outpatient evaluation clinic participated in the study. Subjects received ratings on alcohol and cannabis diagnostic symptoms, recent (past 12 months) drug use frequency, depth of addiction, and recommendation for level of drug treatment. Analysis indicated: (1) the DSM-III-R and DSM-IV have a broader, more inclusive definition of alcohol use disorders than DSM-III; (2) DSM-IV has a broader definition of abuse and a narrower definition of dependence than DSM-III-R; (3) the validity data indicate that all three DSM systems are comparably related to alternate measures of problem severity; and (4) the results were replicated when subjects were analyzed according to their cannabis use diagnoses. (ABL)