In this Unequal Democracies Working Paper, Elif Naz Kayran, European Centre, and Nadja Mosimann, University of Zurich, study the link between trade union power and more inclusive socio-economic rights for foreign workers. The analyses show that trade unions can leverage stronger membership bases and their institutional embeddedness in the decision-making for better socio-economic rights outcomes for foreigners. The findings of the analyses are in line with the arguments developed in earlier case studies concerning the intersection of industrial relations and the politics of immigration. However, the study provides a more complex picture of the influence of trade unions’ power, especially in the decades that follow the 1980s, which seem to diverge from a straightforward relationship between stronger union powers fostering more equal outcomes for the foreign workforce.