In this key work, Robin Cohen shows how the preferences, interests, and actions of global capital, migrant labour and national politicians intersect and often contradict each other. Does capital require subordinated labour? Is it possible for capital to move to labour rather than labour to capital? Can trade substitute for migration? Cohen explores how nation-states segment the "insiders" from the "outsiders" and how politically powerless migrants relate to more privileged migrants and the national citizenry, discussing the functions and effects of social exclusion and deportations. He asks whether politicians can effectively control national borders even if they wish to do so. These important questions are addressed in a wide-ranging, lucid and accessible narrative, offering readers a compelling account of the historical origins and contemporary dynamics of global migration.