This paper studies wage dispersion in an equilibrium on-the-job-search model with endogenous search intensity. Workers differ in their permanent skill level and firms differ with respect to productivity. Positive (negative) sorting results if the match production function is supermodular (submodular). The model is estimated on Danish matched employer-employee data. We find evidence of positive assortative matching. In the estimated equilibrium match distribution, the correlation between worker skill and firm productivity is 0.12. The assortative matching has a substantial impact on wage dispersion. We decompose wage variation into four sources: Worker heterogeneity, firm heterogeneity, frictions, and sorting. Worker heterogeneity contributes 51% of the variation, firm heterogeneity contributes 11%, frictions 23%, and finally sorting contributes 15%. We measure the output loss due to mismatch by asking how much greater output would be if the estimated population of matches were perfectly positively assorted. In this case, output would increase by 7.7%.

We develop and estimate an equilibrium job search model of worker careers, allowing for human capital accumulation, employer heterogeneity, and individual-level shocks. Wage growth is decomposed into contributions of human capital and job search, within and between jobs. Human capital accumulation is largest for highly educated workers. The contribution from job search to wage growth, both within and between jobs, declines over the first ten years of a career—the “job-shopping” phase of a working life—after which workers settle into high-quality jobs using outside offers to generate gradual wage increases, thus reaping the benefits from competition between employers. (JEL J24, J31, J63, J64)