Lead exposure levels have dropped significantly but remain a public health concern due to the widespread prevalence of exposure and the effects of low-dose exposure, for which there is no known threshold. The "Plomb-Habitat" project aims to identify sources of lead in the home, determine their association with blood lead levels, and test techniques for measuring and locating these sources. It is based on a subsample from the "Saturn'Inf" survey on the prevalence of childhood lead poisoning. For the first time in France, environmental measurements conducted in 484 households—representative of the 3.6 million homes housing at least one child aged six months to six years—have made it possible to describe lead contamination in tap water, dust settled on the floor, paint, outdoor playgrounds, common areas, and traditional foods and cosmetics. The Plomb-Habitat project also identified the environmental determinants of blood lead levels, examined the extent to which determining lead isotope ratios in environmental compartments and blood can identify sources of exposure, and compared the information provided by analyses of total and acid-soluble fractions. The development of a model to predict blood lead levels led to the evaluation of lead limit values in drinking water, settled dust, and outdoor soil. The dataset and results compiled through the Plomb-Habitat project can now be used to inform public policy decisions aimed at continuing efforts to reduce lead exposure.