This paper evaluates the effects of a labor market reform in Spain that removed restrictions on fixed‐term or temporary contracts. Our empirical results are based on longitudinal firm‐level data that cover observations before and after the reform. We posit and estimate a dynamic labor demand model with indefinite and fixed‐term labor contracts, and a general structure of labor adjustment costs. Experiments using the estimated model show important positive effects of the reform on total employment (i.e., a 3.5% increase) and job turnover. There is a strong substitution of permanent by temporary workers (i.e., a 10% decline in permanent employment). The effects on labor productivity and the value of firms are very small. In contrast, a counterfactual reform that halved all firing costs would produce the same employment increase as the actual reform, but much larger improvements in productivity and in the value of firms. (JEL J23, J32, J41)