The CDP collected data on externalizing behavior using Achenbach’s (1991, 1997) Child Behavior Checklist (CBCL) and Youth Self-Report (YSR). The Externalizing scale consists of 33 items in the CBCL and 30 items in the YSR and covers both delinquency (e.g., “I cut classes or skip school”) and aggression (e.g., “I am mean to others”). Respondents indicate whether each behavior is “not true,” “somewhat or sometimes true,” or “very or often true.” These measures have been shown to have excellent psycho-metric properties, including high test-retest reliability, content validity, criterion-related validity, and construct validity (Achenbach & Rescorla, 2001, 2003). We created mean externalizing scores by averaging all available parent ratings (CBCL) and youth ratings (YSR) of externalizing behavior across the ages 10 through 17. CBCL ratings (reported by mothers) were obtained for participants at ages 10 through 17, and YSR ratings (reported by participants) were obtained for participants at ages 12, 14, 15, and 16.
