Three measures of friends’ support for substance use were utilized to assess perceptions of substance use across participants’ peer groups as well as the substance use and support of specific close friends. The measures included a self-report of friends’ substance use broadly, a friend report of substance use, and an observed friend drug talk measure. Friends’ support for substance use was measured using questionnaire data collected from participants and from a same-sex, self-nominated friend, and data from the coding of the videotaped Peer Interaction Task (Dishion et al. 1995; Piehler and Dishion 2007) involving the youth and this friend. All data were collected in Grade 11. Participants completed surveys to assess the substance use of their group of friends by using a scale to rate how frequently during the past 3 months their friends used tobacco, drank alcohol, smoked marijuana, or used other hard drugs, with ratings ranging from 1 (never) to 8 (2–3 times a day or more) (α = 0.64, mean inter-item correlation = 0.37) The friend who participated in the videotaped Peer Interaction Task also filled out
