I show that among women likely to use welfare, movers move to higher‐benefit states. I also find that the probability likely welfare users will move at all is lower in higher‐benefit states. This effect is concentrated early in the life cycle, as theory predicts. I construct a theoretical framework to measure the impact of welfare migration on optimal state benefits. Simulation results suggest little impact in higher‐benefit states, but possibly a more substantial impact in other states. Finally, evidence suggests little reason for concern (due to welfare migration) in using cross‐state variation in welfare generosity to identify incentive effects of the welfare system on other outcome variables.