A mail survey was used to investigate 5-year trends in Japanese mothers' reports of their 3-year-olds' cognitive, psychomotor, and social developmental attainment. Findings indicated significant decreases in all domains, not attributable to changes in family structure, although scores were higher among children in nuclear families than in extended families. Findings suggest that national screening programs offer excellent opportunity to assess development or child rearing problems and initiate intervention. (Author/KB)