From 1904 to 1957, the Société Nouvelle du Radium site in Gif-sur-Yvette (Essonne) was home to industrial operations involving the extraction of radium and the production of radium needles. Converted into a residential area starting in 1959, the Petite Coudraie neighborhood underwent successive phases of radioactivity measurements and decontamination work. In 2000, the persistence of radon levels in a residence that were far above health recommendations prompted local authorities to launch a systematic investigation and risk analysis to implement the necessary radiological risk management measures for the entire affected neighborhood. An assessment of the health impact of the site’s contamination was conducted by the Departmental Directorate of Health and Social Affairs (DDASS), the Institute for Public Health Surveillance (InVS), and the Institute for Nuclear Protection and Safety (IPSN). This assessment involved several successive steps: a campaign to measure surface radioactivity on the grounds conducted by the Office for Protection against Ionizing Radiation (OPRI) and the IPSN; a dosimetric study conducted by the IPSN based on the measurement results and realistic exposure scenarios for adults and children present on the site; and a quantitative assessment of cancer risks due to the dose resulting from contamination linked to past industrial activity, carried out by the InVS. This final stage is the subject of this report. This assessment makes it possible to estimate the order of magnitude of the potential health impact associated with the site’s contamination based on the current state of scientific knowledge. It allows for estimating the contributions of various sources of exposure to the risk. It thus helps guide priority management measures. This assessment also enables an evaluation of the relevance of conducting a potential epidemiological study on the population that frequented the site. (R.A.)