When productivity is fostered by both the individual's human capital and by the average level of human capital in the economy, individuals under-invest in human capital. A strictly positive probability of migration to a richer country, by raising both the level of human capital formed by optimizing individuals in the home country and the average level of human capital of non-migrants in the country, can enhance welfare and nudge the economy toward the social optimum. Under a well-controlled restrictive migration policy the welfare of all workers is higher than in the absence of this policy.