title: Terrible ones? Assessment of externalizing behaviors in infancy with the Child Behavior Checklist.
abstract: 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.
  
  
  METHODS
  In a general population sample of 786 12-month-olds, 720 24-month-olds, and 744 36-month-olds, the CBCL/ 1(1/2)-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.
authors.affiliation: Centre for Child and Family Studies, Leiden University, Leiden, the Netherlands. jvanzeijl@fsw.leidenuniv.nl
authors.forename: Jantien
authors.initials: J
authors.lastname: van Zeijl
authors.forename: Judi
authors.initials: J
authors.lastname: Mesman
authors.forename: Mirjam N
authors.initials: MN
authors.lastname: Stolk
authors.forename: Lenneke R A
authors.initials: LR
authors.lastname: Alink
authors.forename: Marinus H
authors.initials: MH
authors.lastname: van Ijzendoorn
authors.forename: Marian J
authors.initials: MJ
authors.lastname: Bakermans-Kranenburg
authors.forename: Femmie
authors.initials: F
authors.lastname: Juffer
authors.forename: Hans M
authors.initials: HM
authors.lastname: Koot
mesh_terms: D000367:Age Factors; D002653:Child Behavior Disorders / Q000175:diagnosis* / Q000453:epidemiology / Q000523:psychology / Q000628:therapy; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D018479:Early Intervention, Educational; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D018730:Infant Behavior; D007389:Internal-External Control; D008297:Male; D009426:Netherlands; D010552:Personality Assessment; D013223:Statistics as Topic