The adoption of the gender parity laws (1999, 2000) stands as an enigma: when it appeared in France in the early 1990s, the motto of parity (statistical equality between the sexes in elected assemblies) was considered utopic, because of its supposed incompatibility with “republican universalism”. This thesis investigates how parity evolved from a marginal claim to a constraining reform. The notion of “space for women's claims making” (espace de la cause des femmes), which designates the groups mobilizing on behalf of women and for women, helps to apprehend both the heterogeneity of actors, sites, and involvements in favor of parity (crossing the boarders between civil society, state, political parties, academic world...), and the links betw...