Studies with nonhuman primates and rodents, as well as with human children, have suggested that early separations from caregivers are often associated with changes in the functioning of the hypothalamus–pituitary–adrenal (HPA) axis. On the basis of these findings, we designed a relational intervention that was intended to normalize HPA functioning among children in foster care. This paper presents findings from a randomized clinical trial that assessed the effectiveness of a relational intervention (Attachment and Biobehavioral Catch-up [ABC]) with regard to HPA functioning. The ABC intervention was intended to enhance children's ability to regulate physiology and behavior. The control intervention (Developmental Education for Families) was intended to enhance children's cognitive skills. A comparison group of children who had never been in foster care was also included. Children's cortisol production was assessed upon arrival at the lab, and 15 and 30 min following the Strange Situation. Random effects analyses of variance were performed to assess differences in initial values and change between children in the two intervention groups. Children in the ABC intervention and comparison group children showed lower initial values of cortisol than children in the treatment control group, considering arrival at lab as initial values (p < .05). Groups did not differ significantly in change over time. These results suggest that the ABC intervention is effective in helping children regulate biology in ways more characteristic of children who have not experienced early adversity.

This paper presents single-subject analyses of newly developing attachment relationships in 10 foster infant–caregiver dyads. Using a diary methodology, at least 2 months of daily data were provided by foster parents on infants' attachment behaviors. Foster infant attachment was also assessed using the Strange Situation. Foster mother state of mind regarding attachment was measured using the Adult Attachment Interview. For eight infants, diary data revealed predominant patterns of attachment behavior emerging within 2 months of placement. In most cases, diary data predicted Strange Situation classifications. Both Strange Situation and diary data indicated that the three children placed in foster care before 12 months of age with foster parents having primary or secondary autonomous states of mind were classified as having secure attachments. The five children placed after 12 months of age showed predominantly insecure attachment behavior in the diary and were classified as insecure in the Strange Situation. Contingency analyses of behavioral sequences reported in the diary revealed that foster parents tended to complement their foster childrens' attachment behaviors.