We created a composite measure of externalizing behaviors/disorders using the first principal component extracted from a principal component analysis. We used both non-clinical and clinical indicators, as age-appropriate, measured in the C-SSAGA interview: (1) alcohol use, (2) marijuana use, (3) cigarette use, (4) DSM-IV clinical criterion counts (American Psychiatric Association 1987) of conduct disorder (CD) criteria, and (5) DSM-IV oppositional defiant disorder (ODD) criterion counts. DSM-IV criterion counts were obtained from the C-SSAGA (Bucholz et al. 1994; Hesselbrock et al. 1999). Alcohol use was measured in the C-SSAGA by asking individuals to report the frequency of past-year drinking on a 12-point scale from 1 (about 1 to 2 days a year) to 12 (every day). Non-drinkers were coded as zero. Marijuana use was assessed by asking participants to report the number of times they used marijuana in the last 12 months. Cigarette use was coded as 1 = past-year use, and 0 = no cigarette use in the past year. We used developmentally-appropriate substance use variables, including alcohol, marijuana, and cigarette use, to capture more variability in risky behavior in
