Young children removed from institutions and placed into foster care or adoptive homes have been shown to experience significant gains in IQ relative to children who remain in institutions. Less is known about the long-term impact of severe early deprivation on development in late childhood. Data are presented from a follow-up of children at 12 years of age in the Bucharest Early Intervention Project, a randomized clinical trial of foster care for institutionally reared children. Of the original 136 children in the study, 107 were tested with the Wechsler Intelligence Scale for Children-IV. Results revealed continued benefit from the intervention through age 12, with 12-year-old children placed in foster care scoring significantly higher on full-scale IQ compared to their peers who received prolonged institutional care. Longitudinal IQ data revealed 2 IQ profiles from early to late childhood. Attachment security emerged as a significant predictor of a profile of stable, typical IQ scores over time. We demonstrate the continued importance of foster care intervention and the negative effects of severe, early psychosocial deprivation on IQ into late childhood.