The study expanded the data-collection efforts of the two previous studies to include the collection and testing of hair specimens to supplement the interview data and urine test data collected in the earlier studies. The results presented in this report were tabulated from the facility's admissions data, interview data self-reported by study participants, and laboratory test results for urine and hair specimens provided by the respondents. Urine specimens were analyzed for the 10 drugs tested for in Drug Use Forecasting programs; and hair specimens were analyzed for marijuana, cocaine, opiates, amphetamines, and PCP. During the study period of May 17, 1994, to October 19, 1994, 200 subjects were approached for the study; eight dropped out prior to being interviewed. Of the remaining 192 subjects, 132 provided a completed interview, urine specimen, and hair specimen. The data presented are derived from this sample. As was found in the previous two studies, this study found that subjects significantly underreported the extent of their drug use. Seventy-five percent of the youths who tested positive for cocaine by hair analysis reported they had never tried cocaine. The same relationships to drug use found in the previous studies were confirmed in this study; however, the increase in drug positives with age usually seen with results from urine testing did not occur with the results from hair testing. By urinalysis, the rate of drug positives went from zero for under age 14 to 36 percent positive for age 18 and above. By hair analysis, 57 percent of those under age 14 had a positive test, but the rate for the remaining age groups was approximately 30 percent. Although currently used mostly for research, hair analysis can be an effective tool for developing a baseline measure and monitoring drug use in a population at high risk for substance use. 5 tables and appended interview form