Thirty adolescent subjects were recruited from an inpatient chemical dependency program. The subjects completed three questionnaires, including the Dimensions of Temperament Scale and the Drug Using Screening Inventory. The substance abusing adolescents were significantly different on six of the nine scales. They scored significantly higher on the scales measuring general activity level whereas they obtained lower scores on scales evaluating flexibility, mood stability, eating rhythms, daily rhythms, and task orientation. Results strongly indicate that substance abusing adolescents are distinguishable from normals on a variety of temperament dimensions. These differentiating characteristics are most closely linked to differences in behavioral activity regulation in as much as it is this aspect of temperament which almost exclusively correlated with severity of drug use involvement and associated disruption in psychosocial adjustment. 3 tables and 11 references (Author abstract modified)