Get access

Terrible ones? Assessment of externalizing behaviors in infancy with the Child Behavior Checklist


Jantien van Zeijl or Judi Mesman, Centre for Child and Family Studies, Leiden University, P.O. Box 9500, 2300 RB, Leiden, the Netherlands; Email: or


Background:  This study investigated the occurrence, cross-informant agreement, 1-year stability, and context characteristics of externalizing behaviors in 12-month-old children, as compared to 24- and 36-month-olds.

Method:  In a general population sample of 786 12-month-olds, 720 24-month-olds, and 744 36-month-olds, the CBCL/1½–5 was obtained from mothers and fathers and again one year later for a subsample of 307 children. Mothers of 1,831 children also provided complete data on child, mother, and family characteristics.

Results:  Over three-fourths of the externalizing behaviors occurred in more than 10% of 12-month-olds, over one-third of the items in more than 25%. For almost all externalizing behaviors, the occurrence was significantly lower in 12-month-olds compared to 24- and 36-month-old children. Mother–father agreement and 1-year stability of externalizing behaviors in 12-month-old children were significant, but generally somewhat lower than in 24- and 36-month-olds. Context characteristics were related to externalizing behaviors in 12-month-olds as well as in older children. Some associations were less pronounced in 12-month-old children, but the overall pattern of correlates was similar across age groups.

Conclusions:  The results of this study show that externalizing behaviors in 12-month-old children merit further research and can be assessed with the CBCL in a valid way.

Get access to the full text of this article