Worker Heterogeneity, Intra-firm Externalities and Wage Compression

We develop a model of monopsonistic wage competition with heterogenous worker ability and intra-firm production complementarities. We use this to illustrate the conditions under which: (i) the divergence between wages and productivity is an equilibrium phenomena; and (ii) this divergence is increasing in worker ability. While the first result is well-known, the second is new. It derives from the intra-firm externalities that, it has sometimes been argued, justify a firm's existence. We show how the model can be used to explain a number of empirical regularities that have hitherto been viewed as puzzles. We then confirm the empirical relevance of our model using new establishment-level data.