All participants were invited to participate in the Peer Interaction Task. Each was instructed to bring a same-sex friend to the research office who was between 14 and 21 years old and had no familial relationship to the participant. The participant and the friend each provided informed consent; if the friend was younger than 18, his or her parents were asked to provide informed consent. A 45-minutes, videotaped discussion between the friends ensued that covered a wide range of topics. The Peer Interaction Task was designed to elicit a wide range of interactive behaviors within the dyad; similar procedures had been used in previous research by Dishion and colleagues (Dishion et al. 1995, 1996, 1997). Eight different topics were discussed for 5 minutes each, and the measure of the friend’s drug use was based on two of these discussions: “drug and alcohol use” and “planning a party.” An interviewer entered the room to end each topic of discussion and to provide the next topic. Both the participant and the friend were compensated for completing the task.
