This article proposes a model with dynamic incentive contracts and on‐the‐job search in a frictional labor market. The optimal long‐term contract exhibits an increasing wage–tenure profile. With increasing wages, worker effort also increases with tenure. These two features imply that the probabilities of both voluntary and involuntary job separation decrease with both job tenure and the duration of employment. Given these results, workers experience differing labor market transitions—between employment, unemployment, and across different employers—and the equilibrium generates endogenous heterogeneity among ex ante homogeneous workers.