Children's attachment to both parents from toddler age to middle childhood: links to adaptive and maladaptive outcomes.

We examined children's attachment security with their mothers and fathers in a community sample (N = 100). At 25 months, mothers, fathers, and trained observers completed Attachment Q-Set (AQS). At 100 months, children completed Kerns Security Scale (KSS) for each parent. Children's adaptation (behavior problems and competence in broader ecologies of school and peer group, child- and parent-reported) was assessed at 100 months. Generally, the child's security with the mother and father was modestly to robustly concordant across both relationships, depending on the assessment method. Observers' AQS security scores predicted children's self-reported security six years later. For children with low AQS security scores with mothers, variations in security with fathers had significant implications for adaptation. Those whose security with fathers was also low reported the most behavior problems and were seen as least competent in broader ecologies, but those whose security with fathers was high reported few problems and were seen as competent. Observer-rated security with fathers predicted children's higher competence in broader ecologies, both self- and parent-reported. A cumulative index of the history of security from toddler age to middle childhood, integrating measures across both relationships and diverse methodologies, was significantly associated with positive adaptation at 100 months.