Migration is a powerful driver and important consequence of economic, political and social change, and there fore needs to be adequately measured and understood. However, the improvement of statistical systems to measure migration has been a slow process because of weak coordination between migration statistics producers, discrepancies in the applied definitions, and challenges related to data collection. The objective of this handbook is to guide statisticians and other professionals in producing and using data on international migration from administrative sources and household surveys in the CIS region. It describes the key concepts and definitions for the measurement of international migration. It also provides practical information on the sources of administrative data and their use, and highlights the related methodological and organizational challenges.