This study is designed to assess the effects of Assessment, Referral, and a Brief Intervention on substance use of individuals screening positive for drug use during a medical ED visit. The Southwest Node of the NIDA Clinical Trials Network, located at UNM CASAA, is taking the lead on this study. Six sites across the country will participate in this study, including the ED of UNM Hospital. A total of 1285 ED patients who screen positive for current drug use problems will be randomly assigned to receive 1) minimal screening only, 2) assessment of substance use and referral to treatment, or 3) assessment and referral combined with a 30-minute counseling session (Brief Intervention) and two follow-up telephone counseling sessions. Outcomes will be assessed at 3, 6, and 12 months after the ED visit. We hypothesize that those who receive the Brief Intervention will have the least drug use at follow-up, that those who receive minimal screening only (the usual current practice) will have the most drug use, and that those receiving assessment and referral without the Brief intervention will have intermediate outcomes.