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 the young sample, rather than using the more severe clinical-level substance use problems as indices of externalizing behaviors, which would yield floor effects in our early adolescent sample. We included a count of DSM-IV CD and ODD symptoms because they index externalizing behavior and problems in youth. Descriptive statistics for externalizing indicators are summarized in Table 1. At T1, the first principal component accounted for approximately 44% of the common variance among the externalizing variables with the following loadings: alcohol use, 0.72; marijuana use, 0.69; cigarette use, 0.75; CD, 0.62; and ODD, 0.49. At T2, the first principal component accounted for approximately 43% of the common variance among the externalizing variables with the following loadings: alcohol use, 0.71; marijuana use, 0.68; cigarette use, 0.70; CD, 0.67; and ODD, 0.51.
