We study different methods of immigration control using a simple model of a congested world. Our main comparison involves quotas, the predominant instrument of immigration control, and a proposed system of immigration tolls and emigration subsidies. We show that the equilibrium of the proposed system is Pareto superior to the quota system. This is consistent with the tolls and subsidies creating a market for international migrants. When countries are price-takers the market becomes perfect and the exploitation of gains from trade complete. From a normative perspective, an open- borders policy is preferred to both control methods but will meet political opposition because it hurts the residents of the rich country.