The economic, social and demographic impacts of migration are large and increasing. Policymakers, researchers and other stakeholders need data on migrants and their integration into societies. These data need be comprehensive, accurate and frequently updated. There is no single source that can provide such data, but by combining several sources together it might be possible to produce the information that users need. Some countries have developed methods for combining administrative, statistical and other data sources for the production of migration statistics. This publication provides an overview of the ways that data integration is used to produce migration statistics, based on a survey of migration data providers in over 50 countries.