We propose a dynamic efficiency wage model with learning by doing. By taking into account the change inthe stock of workers’ knowledge, firms set efficiency wages such that the effort–wage elasticity is not in general equal to one.

Heterogeneous firms facing demand-induced price fluctuations imperfectly compete for heterogeneous workers. It is shown that unemployment may arise in equilibrium because of the combination of uncertainty on product price and mismatch between workers’ skills and firms’ job requirements.