Participants were 82 males and 26 females (n=108) ages 11 to 19 that had been referred for a chemical dependence assessment between June 1999 and June 2000 in Minnesota. The battery of instruments used included the self-administered Personal Experience Inventory and the face-to-face interviewer-administered Drug Use History Interview. Both of these instruments assessed substance-use frequency. Urine samples were also collected as a means of validating self-reports of recent substance use. Alcohol and marijuana use were consistent across both the self-administered questionnaire and the interview format; however, the youths reported higher levels of alcohol and marijuana use in the interview format compared with the self-administered instrument. This finding differs from previous studies that have found higher levels of substance use on self-reports compared with face-to-face interviews. The current study focused on clinic-referred youth; whereas, prior research has focused on community-based populations, suggesting that findings from community-based samples cannot be transferred to clinic-referred samples. Another explanation for the difference in findings from previous research is that the self-report was administered early during the baseline assessment, and the interview occurred later. This provided an opportunity for rapport to develop between the youth and researchers, which may have cultivated greater honesty and accuracy in reporting higher levels of alcohol and marijuana use. 5 tables and 19 references