This book describes how the number of international students has grown in 150 years, from 60,000 to nearly 4 million. It examines the policies adopted towards them by institutions and governments round the world, exploring who travelled, why, and who paid for them. In 1860 most international students travelled within Europe; by 2010 the largest numbers were from Asia. Foreign students have shaped the universities where they studied, been shaped by them, and gone on to change their own lives and societies. Policies for student mobility developed as a function of student demand and of institutional or national interest. At different times they were influenced by the needs of empire, by the cold war, by governments' search for soft power, by labour markets, and by the contribution students made to university finance. Along with university students, others travelled abroad to study: trainee nurses, military officers, the most deprived and the most privileged schoolchildren. All their stories are a vital part of the world's history of education and of its broader social and political history.