I present a model where firms decide what types of jobs to create and then search for suitable workers. When there are few skilled workers and the skilled-unskilled productivity gap is small, firms create a single type of job and recruit all workers. An increase in the proportion of skilled workers or skill-biased technical change can create a qualitative change in the composition of jobs, increasing the demand for skills, wage inequality, and unemployment. I provide some evidence that there has been a change in the composition of jobs in the United States during the past two decades.

This paper argues that a risk-averse worker’s after-tax reservation wage encodes all the relevant information about her welfare. This insight leads to a novel test for the optimality of unemployment insurance based on the responsiveness of reservation wages to unemployment benefits. Some existing estimates imply significant gains to raising the current level of unemployment insurance but highlight the need for more research on the determinants of reservation wages. Our approach is intuitive and complements those based on Baily’s (1978) test. Some advantages of our test are that it uses less of the structure of the model, it is entirely behavioral and does not require separate risk-aversion estimates, and it is robust to various extensions including worker heterogeneity. Shimer’s research is supported by a grant from the National Science Foundation. Werning is grateful for the hospitality of the Federal Reserve Bank of Minneapolis and Harvard University. We are grateful to The goal of this paper is to develop a test for the optimal level of unemployment insurance

In the human capital model with perfect labor markets, firms never invest in general skills and all cost of general training are borne by workers. When lobor market frictions compress the structure of wages, firms may pay for these investments. The distortion in the wage structure turns "technologically" general skills into de facto "specific " skills. Credit market imperfections are neither neccessary nor sufficient for firm‐sponsored training. Since labor market frictions and insititutions shape the wage structure, they may have an important impact on the financing and amount of human capital investments and account for some international differences in training practices.