The data were collected in the context of a referral and assessment program for adolescents suspected of using drugs. The data-collection instrument was the Adolescent Substance Battery, which quantifies the level of drug impairment experienced by the adolescent and the level of treatment needed. Substance abuse and chemical dependency diagnoses were based on criteria in the Diagnostic and Statistical Manual, Fourth Edition. Two psychometric instruments were used as part of the battery to assess defensiveness. A census district sample for randomly selected schools was obtained. A school was defined as grades 6 through 12. Census data showed the study sample to be approximately representative of students living in the Pacific Northwest. Of these, 1,637 were assessed for suspected drug use, including 654 middle school students (40 percent) and 983 high school students (60 percent). A random 20 percent of the assessed adolescents were targeted for urine sample collection. A total of 296 urine samples were collected, representing 18 percent of the total sample and 90 percent of participants targeted for urine collection. Urine samples were quantitatively screened for pharmaceuticals using a standard thin-layer chromatography technique. Statistical significance was found in the relationship between gender and marijuana use. This study confirms that gender and drug-using behaviors among adolescents need additional research and evaluation. 7 tables and 42 references