In this proposed randomized trial, a one-way design (MI + Standard Care [SC] v. Attention Control [AC] + SC) will be used to determine whether MI enhances subsequent treatment participation and reduces substance-related problems post discharge in substance using, delinquent youths. Teens will also receive a booster session of MI or AC prior to discharge. Primary outcome variables include alcohol and marijuana use, as well as related behaviors (illegal activity, sex or injuries while drunk or high). It is hypothesized that in comparison to teens receiving AC, youths receiving MI will participate more (by therapist and teen ratings) in SC and will show the lowest levels of heavy substance use and related problems after discharge. It is hypothesized that these effects will be mediated by stage of change, drug effect expectancies and self-efficacy.