The externalizing behavior scores at age
3 and age 9 drew on items asked of the
mother from Achenbach and Rescorla’s
CBCL. At age 9, the externalizing measure
drew on 35 items that make up
the aggression and rule-breaking subscales
in the CBCL. At age 3, the measure
was based on 24 items from the in-home
interview, including the 19-item aggression
subscale and the 5 unique items
from the destructive subscale not included
in the aggression subscale.