Emigration, both politically and economically determined, has always been a phenomenon firmly present in the history as well as in the consciousness of the Poles. Throughout Polish history migration flows were initiated either by political factors (dissidents fleeing political repressions at the hands of the occupants or the communist regime) or economic ones (peasants of the overpopulated countryside leaving 'in search of bread'). The result of more than 100 years of intensive emigration was the development of a Polish diaspora spread throughout the world (Walaszek 2001); the building-up of migration networks facilitating foreign migration and the generation from international migration of an easily available means of accumulating capital and resolving short-term economic difficulties.Notwithstanding the scale and significance assumed by migration, accessible statistical data do not allow for an accurate estimation of the flows to and from Poland. Measurement of foreign migration is based first and foremost on registration and deregistration, rather than on people's real movements. Data from various sources are not compatible, and frequently even conflict with one another (Sakson 2002). This in part due to methodological limitations (with information on migration being collected ex ante, which is to say that a person who intends to emigrate declares both that intention and the planned length of stay), but also to some extent reflects economic considerations (other forms of measurement like the British International Passenger Survey are very costly), as well as civilisational changes shaping new forms of international mobility (i.e. circular or irregular migration), that fall outside the definitions and methods of measurement employed hitherto.