An epidemiological study conducted in four departments with the support of the Directorate General of Health has revealed a problem of childhood lead poisoning in Lyon, a problem closely linked to the type of housing occupied by the families concerned (the age of the buildings, which indicates the use of lead-based paint, and their dilapidated condition). The article describes the response measures and on-the-ground initiatives implemented by agencies working with children and their families (Maternal and Child Health Services, Social Development Services), with support from the Rhône Departmental Association for Health Education and the Lyon Association for Social Integration through Housing. Accurate determination of the incidence of lead poisoning through screening has enabled the targeting of a rehousing policy and health education initiatives for families. A technical lead committee initiated by the government plays a coordinating role. The initial results are presented.