Migration to the cities had been a part of European rural life long before the start of modern industrialisation and urbanisation. In the era of modern development, however, rural-urban migration intensified in an unprecedented way and many rural communities depopulated. While during the pre-industrial period migration had contributed to the economic and social reproduction of rural communities, it now challenged the continuity of the rural lifestyle. This book analyses the topic for the case of Spain, which in the twentieth century experienced one of the most intense processes of rural depopulation in modern Europe.