Developmental psychologists and educators assume that early experiences shape the brain and neural circuitry for emerging cognitive and social behaviors over the first years of life. Most of the evidence for these assumptions is based on rodent and non human primate animal research. Far less has been published on the effects of early experience that is not correlational in nature. The Bucharest Early Intervention Project (BEIP) is the first randomized trial of a family intervention for children who experienced significant psychosocial neglect early in their lives. A group of infants living in institutions in Romania were recruited and randomized to be taken out of the institution and placed into family/foster care homes or to remain in the institution. Follow up of these children occurred at 42 and 54 months of age and at 8 years of age. Multiple domains, including cognitive, socio-emotional, psychiatric, and brain imaging were assessed at each age. Three questions are posed in this study and this talk: first, are there lasting effects of early psychosocial deprivation as children develop over the school years. Second, is intervention successful in ameliorating deficits as a result of institutionalization. And third, are there sensitive periods in delivering the intervention that explain both success and failure to improve cognitive and socio-emotional behavior.