The purposes of this study were: (1) to determine if juvenile detainees with higher levels of drug use severity were more likely to be classified as chemical abuser (CA) or chemical dependent (CD) by SASSI; and (2) if so, how SASSI could be used to identify subgroups of juvenile detainees most at risk for substance misuse. Data were collected from 196 female juvenile detainees during a six-month period in 1994. The 78-item SASSI has two sets of scales -- the “subtle” scales that are designed to detect substance users who are denying or attempting to conceal their substance use, and the “face valid” scales that ask direct questions about substance-related problems and are designed to identify users who report accurately. A questionnaire was administered, and urinalysis and hair analysis specimens were taken. These findings might not apply to male juvenile detainees. Based on the information from the interview and hair analyses, almost all of the female juvenile detainees in the sample had used soft or hard drugs. Most of the hard drug users (those who used cocaine, crack, opiates, LSD, and PCP) had used multiple drugs and had used them recently. The SASSI enabled the identification of groups of youths containing a high percentage of hard drug users. When resources for drug prevention, assessment, or treatment are very limited, only a fraction of those in need can receive services. In this situation, administrators could use the SASSI to identify a relatively small group of youths containing the highest possible percentage of hard drug users. When resources are more plentiful and services can be provided to a greater proportion of youths that might need them, a less stringent selection criterion could be used. This study shows the value of using biological measures in addition to self-report information to identify hard drug users in the juvenile detainee population. 1 figure, 6 tables, 54 references