Externalizing problems were measured by the Externalizing subscales on the developmentally-relevant Achenbach scales annually from ages 5–27 (except ages 18, 25, and 26): Mothers’ scores came from the relevant factor of the Child Behavior Checklist (CBCL, 33 items; Achenbach, 1991a) from ages 5–17; teachers’ scores from the Teacher Report Form (TRF, 34 items; Achenbach, 1991b) from ages 5–13; fathers’ from the CBCL from ages 5–9 (only for cohort 1 at age 9); self-reports from the Youth Self-Report (YSR, 30 items; Achenbach, 1991c) at ages 12, 15–17, and 19, and the Young Adult Self-Report (YASR, 28 items; Achenbach, 1997) from ages 20–24 and 27; peer reports from the YASR at age 27. In each of the scales, reporters rated whether a given behavior was “not true,” “somewhat or sometimes true,” or “very or often true” (scored 0, 1, and 2, respectively).
