The distribution and the statistical accuracy of scores on the Drug Use Screening Inventory (DUSI) and the discriminative power of the DUSI for identifying individuals who qualify for a DSM-III-R diagnosis of Psychoactive Substance Use Disorder (PSUD) were examined in 846 adolescents. The subjects with PSUD had higher mean scores, and the distribution of their scores approximated a normal distribution in each of the 10 domains measured by the DUSI. All of the DUSI domains yielded more precise trait estimates for the subjects who had more severe PSUD. Within the normal sample, using a score of 30 on the overall problem density index as the cutoff score, the DUSI correctly classified 95% of the normal sample and 81% of the PSUD cases.