OBJECTIVE: To investigate the differences of psychological and behavioral development between children aged 1 to 3 years fostered by grandparents and those by parents. METHODS: Psychological and behavioral development of 443 children aged 1 to 3 years fostered by their grandparents and of aged-matched 443 children fostered by their parents were assessed with DST, an intellectual developmental screening test developed by Pediatric Hospital of Fudan University in Shanghai. RESULTS: The abilities of social adaptation and intelligence development in children fostered by their grandparents were obviously retarded as compared with those in children fostered by their parents. CONCLUSIONS: There are shortcomings in psychological and behavioral development in children aged 1 to 3 years fostered by grandparents.［Chin J Contemp Pediatr, 2009, 11 (12):1006-1007］