1The 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).

2The 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.

3The 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 Université catholique de Louvain (B. Schoumaker),
• in Spain, the Universitat Pompeu Fabra (P. Baizan) and the Consejo Superior de Investigaciones Científicas (A. González-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 Université Cheikh Anta Diop (P. Sakho).

4Thanks 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). The project provides a unique opportunity to analyse populations living in different countries – migrants interviewed in Europe, return migrants and non-migrants interviewed in Africa – and this is without doubt its major strength. By combining different samples, both the causes and consequences of migration can be studied, and the effects of national contexts on migration processes, both at origin and at destination (migrants from each group – Congolese, Ghanaian and Senegalese – were surveyed in at least two different European countries) can be explored by comparing the various groups. This special feature includes a detailed and critical overview of the project methodology (Beauchemin).

5The data collected in Africa and Europe were designed to provide scope for original analyses in four main areas: migration patterns, the determinants of different types of migration (departure, onward migration, return), the effects of migration on family life, and the economic impact of migration on migrants and their families. The articles in this special feature address some of these topics and illustrate the varied strands of research spawned by the MAFE project. They are just a small sample of the diverse publications – journal articles, books, book chapters, working papers, academic research papers – that report the MAFE project findings. A full list is available on the MAFE website (http://mafeproject.site.ined.fr/). The articles included in this feature will not be described here, but their most salient commonalities deserve to be highlighted.

6The first commonality is the finding that sub-Saharan migration cannot be described as a one-way flow towards Europe. Three “key moments” of the migration trajectory are examined: (1) Sophie Vause and Sorana Toma analyse migrant departures from Senegal and DR Congo to test the hypothesis that female migration is increasing and that more women are migrating independently; (2) Sorana Toma and Eleonora Castagnone study Senegalese onward mobility and show that the destination country is not necessarily the country of settlement; and (3) Marie-Laurence Flahaux reveals the relatively high level of return migration among Congolese and Senegalese migrants.

7Second, the four thematic articles in this feature all confirm, yet again, the importance of the family and social environment in the organization of international migration. Vause and Toma show that the emergence of autonomous female migration from DR Congo is spurred by the existence of social networks in destination countries, a finding which raises the question of what “independent” migration actually signifies. Social networks also play a decisive role in intra-European mobility of African migrants: having relatives or friends in a country other than the destination country is a factor associated with onward mobility among Senegalese migrants who arrive in Spain, France or Italy (see the article by Toma and Castagnone in this volume). The absence of friends or family in Europe (spouse, children) is a determinant of return (article by Flahaux), a finding which reminds us that family reunification can occur in the country of origin as well as at destination (Baizán et al., 2014). While social networks and family situation are clearly key factors behind the various forms of mobility, this mobility also affects migrants’ family life, as shown by Kim Caarls and Valentina Mazzucato in their study of the impact of migration on divorce risk.

8The third commonality is methodological. The articles clearly illustrate the advantage of working with retrospective data from a multi-site survey, i.e. conducted at both origin and destination, to study international migration. The detailed study of the determinants of return migration, taking account of migrants’ initial intentions, would not have been possible if the sample used by Marie-Laurence Flahaux had not included life histories of both migrants still in Europe and migrants who had returned to DR Congo and to Senegal. Likewise, for the study of the effects of migration on divorce, it was essential for Kim Caarls and Valentina Mazzucato to dispose of a transnational sample to compare non-migrant couples and couples with international migration experience (joint experience, or of one partner only). Nor would these studies have been possible without a life event history approach that allows researchers to analyse life trajectories and the timing of migration with respect to other events that structure migrants’ lives.

9The articles in this feature all illustrate the remarkable potential of the MAFE survey data. While the initial aim of this project was to study international migration, many related topics still need to be explored. The MAFE data lend themselves to the study of numerous other sociodemographic phenomena (entry into union, fertility, infant mortality, labour market access, etc.). The African samples offer considerable scope for the study of non-migrant populations in the three capitals covered in the survey, Accra, [3] Dakar and Kinshasa (including or excluding the samples of migrants in Europe to control for migration-related selection effects). The micro and macro project data are now available to the research community in both French and English, and we hope that they will be the starting point for many future studies. [4]