For a long time the early modern population of North Western Europe has been looked upon as fairly sedentary. Although since the 1980s new research has shown that people were much more mobile than was earlier acknowledged, in many historical works either the industrial revolution or the Napoleonic period continue to be regarded as a caesura in the migratory behaviour of people. In this dissertation the size, direction and the mechanisms behind the pre-industrial migrations from the countries bordering the North Sea for a period of over 250 years (ca. 1550-1800) were under scrutiny. The reconstruction of the size and direction of the migration flows showed that the migrations that took place within the North Sea area were larger than to other destination in the world, like for instance the America's. The main pole of attraction for most of the emigrants from the surrounding countries was the Dutch Republic; it was the centre of what can be labelled a North Sea migration system. With its booming economy in the seventeenth century and still plentiful job opportunities in the century that followed, it attracted the lion's share of emigrants from the surrounding countries. Apart from the opportunities to find employment, the high wages were an important incentive for people to move to the Dutch Republic. On the sending side, especially demographic pressure resulting in overcrowded labour markets and low wages stimulated out-migration; the Dutch Republic was the logical destination. Interestingly, a shift in the type of migrants took place from the end of the eighteenth century. While before migrants predominantly settled after moving to the Dutch Republic, during the eighteenth century increasingly people worked without actually settling abroad; especially the maritime labour market provided opportunities for this. Therefore, although the share of migrants living in the Netherlands dropped very quickly after c. 1650-1670, the number of migrant that actually worked there did not decline that much. On the other side of ...