This paper is one of the first to use employer-employee data on wages and labor productivity to measure discrimination against immigrants. We build on an identification strategy proposed by Bartolucci (2014) and address firm fixed effects and endogeneity issues through a diff GMM-IV estimator. Our models also test for gender-based discrimination. Empirical results for Belgium suggest significant wage discrimination against women and (to a lesser extent) against immigrants. We find no evidence for double discrimination against female immigrants. Institutional factors such as firm-level collective bargaining and smaller firm sizes are found to attenuate wage discrimination against foreigners, but not against women.