Recent theories of the social consequences of institutions point to aspects of class and ethnic relations that are not fully captured by conventional institutional perspectives. Using some of these recent theoretical contributions, this thesis analyzes the influence of institutional conditions on the mobilization of French and immigrant workers in late 19 th -century northern France. Two main institutional structures are discussed: Frances unique network of labour courts, and the socialist cooperatives created by Flemish workers in the 1880s. The empirical, chiefly archival evidence suggests two main conclusions: labour movements emerged and evolved strongly influenced by the judicial framing of labour relations, which they in turn sought to use and modify to their advantage; the institutional innovation of Flemish immigrant workers had a durable influence on the organization of labour politics in northern France, and contributed to their integration as active social and political participants.