Cross-border mobility among students is a key instrument in favoring peace between European countries: discovering that they share a common culture, common values, and, despite a history of wars and conflicts, knowing that they have much to gain by building a cooperative future together. For this reason at least, cross-border mobility among students is politically desirable. In addition, student mobility is a driver for the future circulation of ideas, innovation and graduates. It is a way of creating a single market for highly skilled people and aligning the mobility of labor with that of productive activities. This may mean brain drain within Europe, at least for a time, but also brain gain for Europe as a whole. Therefore, there is room for a two-dimensional economic reading of student mobility: the efficiency of the organization of the higher education system, and the equity or fairness between individuals and between countries. In this paper we question student mobility in regard to both economic efficiency and fairness. For this purpose, we do not limit ourselves to theoretical considerations, but, instead, we contemplate statistics and institutions, develop an assessment of the mobility at stake, and make some recommendations for higher education policy.