We use twenty years of Italian administrative panel data, a uniquely rich source of information on internal migration experiences, to identify the role of unobserved worker characteristics in the selection and returns to migrants. We propose and implement a novel iterative estimation method for a switching regression model with the same worker-specific source of unobserved heterogeneity ("ability") present in the selection and both outcome equations. We estimate that the returns to ability are lower in the North than in the South of Italy and accordingly migrants tend to be drawn from the lower-end of the ability distribution. Around half the gains to migration are due to higher wages, and the other half due to greater labor market attachment. Differential returns to observable characteristics are far less important. Return migration reinforces the original negative selection of migrants, consistent with migrants facing considerable uncertainty about their income in northern Italy.
