Founded in 2000, the Alliance for Rare Diseases emerged from the shared determination of a handful of rare disease associations that recognized their isolation. Each of them represented too few patients to attract the attention of public authorities, the medical profession, research institutions, or the pharmaceutical industry. By uniting the voice of 240 associations of people affected by rare diseases, whether identified or not, the Alliance for Rare Diseases contributes to improving the quality of life for all sick individuals. It fights for an equitable society where each person's civic participation and collective action advance the common good, solidarity, and knowledge. As the legitimate spokesperson for the 3 million French people affected by rare diseases, it informs and challenges the public sphere, healthcare professionals, and institutional bodies. Its associative expertise has a direct impact on public health policies and promotes advances in clinical and scientific research.