The target population consisted of 426 juvenile detainees, between 14 and 18 years old, who were located at two sites: Cleveland, Ohio (185 male detainees), and St. Petersburg, Fla., (241 male and female detainees). Following an interview and collection of a urine specimen, hair specimens were obtained, and the COMPASS assessment was administered to all subjects. Urinalysis was performed by using EMIT, an objective, machine-readable method. Specimens were analyzed for the 10 drugs standard to the Drug Use Forecast system: cannabinoids, cocaine, opiates, PCP, methadone, amphetamine, diazepines, methaqualone, barbiturates, and phenylpropanolamine. Hair specimens were analyzed for evidence of cocaine, marijuana, methadone, PCP, and opiates, using radioimmunoassay screening and gas chromatography/mass spectroscopy confirmation analyses. Hair analysis identified higher drug prevalence for cocaine than did urinalysis, a finding consistent with the data reported in the original study; however, the findings for marijuana were inconsistent. Virtually all subjects had high COMPASS scores relative to the general population norms for the instrument, showing that youths at both sites were at risk for substance abuse. In this regard, the assessment instrument was successful. High risk was indicated without reference to either the bioassay or self-report outcomes; however, COMPASS did not finely differentiate among the juveniles in the sample. Implications of these findings and further research are discussed. 2 notes