The present study examined the social skills of previously institutionalized, 8-y-old Romanian children from the Bucharest Early Intervention Project and the influence of attachment security and brain electrical activity (alpha power) on these skills. Participants included children randomized to an intervention involving foster care [Foster Care Group (FCG)], children randomized to remain in institutions [Care As Usual Group (CAUG)], and neverinstitutionalized children living with their families in the Bucharest community [Never-Institutionalized Group (NIG)]. A continuous rating of children's attachment security to their primary caregiver was assessed at 42 mo of age. When children were 8 y old, teachers rated their social skills, and the children's resting electroencephalogram alpha power was recorded. Teachers rated social skills of FCG children who were placed into foster care before 20 mo of age as no different from NIG children, and both of these groups were higher than CAUG children and FCG children placed after 20 mo. Electroencephalogram alpha power at age 8 significantly moderated the relations between attachment security and social skills. These findings characterize institutionalized children's social skills in middle childhood within the context of a randomized intervention while highlighting the roles of both relational and biological factors in these developmental trajectories.social behavior | neglect | early experience T he present study examined 8-y-old children who had a history of institutional rearing to better understand the impact of this early experience on social skill development in middle childhood. Specifically, we examined the timing of an intervention (placement into a foster care home), as well as attachment security with the primary caregiver at 42 mo and children's brain electrical activity in relation to teacher-rated social skills at 8 y of age.Considerable research has been conducted examining the consequences of severe emotional and physical deprivation associated with institutional rearing across physical, cognitive, and social domains (e.g., 1-4). Recently, these findings have been augmented by demonstrations of abnormal brain structure and functioning following severe early deprivation (5-10). Across these studies, several factors appear to influence outcomes, for example, age of placement into an institution (11), timing of removal and placement in a family (2), and sex of the child (12).Additional work has focused on social developmental outcomes following institutional rearing. Many studies have characterized children's attachment relationships formed with institutional (13, 14), adoptive (15), or foster (16, 17) caregivers. These studies have documented profound problems in the attachment relationships that young children form with caregivers following early deprivation. In addition, these children are reported to display abnormal social behavior toward adults (e.g., 18-20). Additional research has examined the social behavior of institutionalized children among their ...