The role of immigrants in the making and remaking of labor forces and labor movements has given rise to manifold studies in social sciences on an international level. The role of "organizing" immigrants in the revitalization of trade unions has been analyzed by specialists of trade unions and social movements. If the role of immigrant workers in the social and economic history of Luxembourg is acknowledged, the history and sociology of trade union representation and organization of immigrants is little studied. LUXTUI will analyze the contemporary role of trade unions as a vector for professional as well as social and political participation and representation of immigrants in Luxembourg. In the context of a multinational structure of wage earners in Luxembourg (43.7%) of jobs in 2008 were occupied by cross-border workers, 27% of jobs by immigrants and 29.3% of jobs by national workers), the research project will analyze the provision of services to immigrants by trade unions and he organization of immigrants inside of union structures, as well as the way trade unions represent, in interaction or in competition with other social and political actors, immigrants' interests. This organizational and political analysis of trade unions will be completed by an analysis of individual trajectories of trade union representatives and activists with a migration background. The project will mainly mobilize qualitative research instruments from the fields of political science and sociology. LUXTUI will allow a better understanding of the role of trade unions in the integration process of immigrants. It contributes thus to the sociology of industrial relations, of trade unionism and of immigrants' political participation. Th project will also contribute to the growing body of studies on union revitalization which is concerned among others with the recruitment of immigrants in trade unions.