The Directorate General for Health and the National League Against Cancer commissioned the RESSCOM association to conduct a study on the factors contributing to the non-participation of women aged 50 to 69 in breast cancer screening campaigns. This survey (qualitative and quantitative) was conducted in 1998 in four departments: Allier, Loire, Rhône, and Val d'Oise. The analysis reveals two profiles of women who, for social and cultural reasons, do not participate in organized screening campaigns: the most socially advantaged (women who are “masters of their own destiny”) and the most disadvantaged (women who are “vulnerable”). In conclusion, the authors make recommendations likely to improve women’s participation.