This study is concerned with the reason why about 60,000,000 people left Europe for overseas destinations. The key issue is taken to be the incidence of emigration, that is, why did some people emigrate and not others? The book, which is based on research findings from more than twelve European countries, shows that the economic and social characteristics of the regions from which the emigrants came are not an adequate explanation of the rate of emigration. This raises questions about the importance of information and the chain migration. The fact that return migration was common has important implications for the causes of emigration. Were the majority of returned migrants failures or had many made the decision to return before they left Europe? A further important issue is the relation between economic growth in Europe and emigration. In particular, did migration to the circles inhibit or encourage emigration? Finally, the book discusses the economic effects of immigration on the receiving countries and the social experience of the immigrants.