At least 10 million Mexicans live in the United States today and they are joined by as many as 400 000 every year. They affect the Mexican economy both through the labour market -- the balance of emigration and return migration influences the level of the labour supply and its composition -- and through remittances, which are important in household incomes and the balance of payments. Migration also plays an important role in the increasing integration of the Mexican and US economies, a process also spurred by NAFTA. This chapter reviews the main characteristics of migration in Mexico and then discusses migration policies in Mexico and in the United States insofar as they affect Mexico. The last section turns to economic aspects of migration, including those associated with illegal entry into the United States, labour market incentives and impacts, human capital issues and remittances...