and peer relationships). Fourth, the finalized revision of each diagnostic module was reviewed for meaning, logic, and comparability to the adult version. Each diagnostic section was then systematically piloted to test the flow and timing among adolescents, with subsequent modifications to reduce the length of the diagnostic sections. Lifetime substance use disorders assessed in the CIDI included alcohol and drug abuse, and individuals fulfilling abuse criteria were administered questions concerning dependence criteria. This report therefore presents both categories of abuse (with or without dependence). In light of differences in the pertinence of diagnostic categories for nicotine, trajectories for this substance will be addressed in a separate manuscript. In addition to DSM-IV diagnoses, all respondents were asked about the use of diverse substances and their age at which specific stages of use first occurred. For alcohol, the lifetime use question concerned age at which respondents first (if ever) had a drink with alcohol, specified as beer, wine, wine coolers, and hard liquor (eg, vodka, gin, whiskey, and mixed drinks). First regular use of alcohol was defined as the age at which the respondent first had at least 12 drinks within a single year. For illicit drugs, participants were asked their age
