International migration figures prominently on the agenda of the United Nations. Solid migration data are crucial for supporting this global debate. This article describes the international migration data sets produced by the Population Division, Department of Economic and Social Affairs, United Nations. The Population Division’s Migration Section produces migrant stock estimates for the world’s countries by sex and, more recently, by age. The Section also produces a database containing annual data on inflows, outflows, and net flows of international migrants by country of origin for major destination countries. The Section maintains the Global Migration Database, containing the world’s most complete set of empirical statistics on the international migrant stock by country of birth, citizenship, sex, and age for more than 200 countries and territories for recent decades. The data and associated publications are available from the Migration Section’s Web site at http://www.unmigration.org.