The fact that immigration is just one component of international migration might appear self-evident. Demographers know well that migration flows operate in more than one direction, and that they are reversible. Indeed, this is what makes the study of migration so complex. Yet the most commonly available data are those produced in destination countries, so research tends to focus on immigration rather than emigration. With statistical production limited to the data collected by immigrant receiving countries at their national borders, immigrants' subsequent movements - be they returns to the country of origin or onward migration to a new destination - have received little or no attention. In most cases, they are simply not measured. In fact, very few countries record departures from their territory (emigration flows), and the dispersion of their emigrants (expatriate nationals or departed immigrants) makes the counting of emigrant stocks difficult to say the least.(1) The fact that sources and statistical studies focus so strongly on migration within nation-states has been conceptualized as a form of methodological nationalism (Beauchemin, 2014; Wimmer and Glick Schiller, 2003). This has a knock-on effect on attitudes to international migration, contributing to the general perception that immigration is a one-way process, and that newcomers' sole intention is to settle permanently in the host country. Graeme Hugo denounces what he calls settlement bias in the perception of migration, which consists in neglecting its reversibility (Hugo, 2014).The MAFE project took shape in the mid-2000s, at a time when European public debate was preoccupied by fears of an African invasion (de Haas, 2008 ; Lessault and Beauchemin, 2009). Its initial ambition was to go beyond a one-sided approach to international migration, to study not only migration from Africa to Europe, but above all migration between Africa and Europe. Defined in this way, the project appears truly vast in scope. In fact, it is limited to the study of international migration by people from three countries: Ghana, the Democratic Republic of Congo and Senegal. And while emigrants from these countries head for wide-ranging destinations, the project focuses above all on Europe.The aim of studying migration between Africa and Europe more generally, rather than focusing in immigration, called for a multi-sited approach to international migration, and for the collection of new data at both origin and destination. Following the example of comparable surveys conducted elsewhere in the world, notably in North America and Latin America,(2) a large-scale survey was designed by the French Institute for Demographic Studies (INED) in collaboration with partners in Europe and Africa. A wide range of institutions on both continents are involved:* in Belgium, the Universite catholique de Louvain (B. Schoumaker),* in Spain, the Universitat Pompeu Fabra (P. Baizan) and the Consejo Superior de Investigaciones Cientificas (A. Gonzalez-Ferrer),* in France, French Institute for Demographic Studies (INED) (C. Beauchemin),* in Ghana, the University of Ghana (P. Quartey),* in the United Kingdom, the University of Sussex (R. Black),* in Italy, the Forum Internazionale ed Europeo di Ricerche sull'Immigrazione (E. Castagnone),* in the Netherlands, Maastricht University (V. Mazzucato),* in the Democratic Republic of Congo, the University of Kinshasa ( J. Mangalu),* and in Senegal, the Universite Cheikh Anta Diop (P. Sakho).Thanks to this broad-based partnership, the same survey protocol could be applied in all the countries involved. The MAFE project thus disposes of data that are comparable (identical questionnaires were used in the various countries), longitudinal (retrospective), and multi-level (data collected from individuals and households are associated with contextual, social, economic and political data at national level). …