Previous research confirms that many employees work in jobs not well matched to their skills and education, resulting in lower pay and job satisfaction. While this literature typically uses cross-sectional data, we examine the evolution of mismatch and its consequences over a career, by using a panel data set of scientists in the USA. The results show that both the incidence of mismatch and its negative consequences appear concentrated among those late in careers. This suggests that past studies of mismatch may exaggerate the degree of inefficiency in labor market matching. (Contains 5 notes, 9 tables, and 2 figures.)