This paper studies the labor market effects of migration-related supply shocks. We exploit forced migration caused by the Colombian conflict as a natural experiment to examine the impact of exogenous labor supply shifts on labor outcomes. While migration flows are exogenously produced by conflict dynamics, location decisions might be positively correlated with demand shocks. An instrumental variables strategy allows us to correct for the possible attenuation bias generated by internally displaced populations locating in dynamic labor markets. Our results suggest that these immigration flows produce large negative impacts on the wages and employment opportunities of all workers, and are particularly large for low skill workers.