This article presents a formalized field theory of international migration. Departing from the theories of Kurt Lewin, the author assumes that the valences of different migration targets create a field of attracting forces, which may trigger long-range “locomotions.” Moreover, the author hypothesizes that the selection among the different migration targets also depends on the perceived opportunities: the higher the number of vacancies at a target and the stronger the reporting about these vacancies by earlier migrants, the stronger the field of perceived opportunities. A mathematical model based on these theoretical assumptions is tested with data about migration from Poland to other EU countries. The goodness of fit of the model is quite high and seems to corroborate its field theoretical foundations. The model is further explored by simulating its behavior for different scenarios of valences and perceived opportunities. The article finishes with a summary from the perspective of analytical sociology.