We quantify firm heterogeneity in skill returns and present direct evidence of worker–firm complementarities. Using population data linked with cognitive and noncognitive skill measures, we estimate a model of firm-specific returns to these attributes. We find evidence of significant return heterogeneity, sorting, and earnings convexification: (1) Skills command different returns across employers; returns to the two skills correlate weakly within-firm. (2) Workers with large endowments of a skill populate firms with higher returns to it. Sorting intensity grows with cross-sectional dispersion of that skill return. (3) Complementarities and sorting have nonmonotonic effects, raising both level and skewness of earnings.