Lead exposure adversely affects the cognitive development and behavior of young children (1). For children aged < 6 years, CDC has defined an elevated blood lead level (BLL) as > or = 10 microg/dL, but evidence exists for subtle effects at lower levels (2). Data from CDC's Third National Health and Nutrition Examination Survey, Phase 2 (1991-1994) (NHANES) showed that average BLLs in children had decreased approximately 80% since the late 1970s but that elevated BLLs remained more common among low-income children, urban children, and those living in older housing (3,4). Although these data provide national estimates of the prevalence of elevated BLLs among children, they do not provide information at the state or local level. To target prevention efforts and monitor progress toward reducing BLLs at the state and local level, CDC's Childhood Blood Lead Surveillance (CBLS) program supports state blood lead surveillance programs on the basis of blood lead tests from public and private clinical laboratories. This report summarizes data on BLLs in children aged 1-5 years from NHANES data collected in 1999 and children aged < 6 years from state surveillance data provided to CDC by 19 state surveillance programs during 1996-1998. The findings indicate that, despite the decreases in mean BLL among children, the problem remains concentrated on a local level. Surveillance efforts should be used to target screening efforts to communities at highest risk.