1This special issue of Population is devoted entirely to the EPIC survey on individual and conjugal trajectories (Étude des parcours individuels et conjugaux), the third large-scale French survey on union formation after Choice of Spouse (Le choix du conjoint, 1959) and Couple Formation (La formation des couples, 1983-1984). The survey was conducted in metropolitan France in 2013–2014 by the French Institute for Demographic Studies (INED) and the National Institute for Statistics and Economic Studies (INSEE) [1] among 7,825 women and men aged 26–65. Rather than focusing on a single theme, the seven articles in this issue explore a range of subjects, illustrating the broad research potential of the EPIC survey data. Following a discussion of the survey’s background, design, and methodological choices in the opening article (Wilfried Rault and Arnaud Régnier-Loilier), the topics covered include wedding rituals and the ways marriage is celebrated (Florence Maillochon), the influence of conjugal history on the repartnering process (Arnaud Régnier-Loilier), experiences of singlehood (Marie Bergström, Géraldine Vivier, and Françoise Courtel), the effects of longer periods in education on assortative mating (Milan Bouchet-Valat and Sébastien Grobon), second unions (Vianney Costemalle), and same-sex relationships (Wilfried Rault and Camille Lambert).

2Alongside these specific analyses, the articles in this issue illustrate the wide range of approaches now used to explore union formation and conjugal relationships. Several studies are based on data drawn from EPIC’s most noteworthy innovation, the ‘history of unions or serious intimate relationships’ (historique des relations de couple et relations amoureuses importantes) module that recorded respondents’ conjugal histories. Thanks to its strong retrospective dimension, data from this module can be used, for example, to study changing trends in assortative mating according to the context in which couples meet (Bouchet-Valat and Grobon), differences between first and second unions (Costemalle), or the factors behind the formation of new cohabiting or noncohabiting unions (Régnier-Loilier).

3Several articles focus on how the EPIC survey ties in with other research findings. Bergström, Vivier, and Courtel analyse data from another innovative EPIC module administered to unpartnered individuals, in association with a series of in-depth qualitative interviews conducted on a subsample of respondents after the main survey. This approach sheds new light on the statistical findings and provides a more accurate picture of the diverse situations of singles, an ever-increasing population largely overlooked by sociologists and demographers.

4The articles by Maillochon and by Rault and Lambert compare EPIC’s findings with those of earlier surveys on similar themes. Further to Michel Bozon’s research on the sociology of marriage and wedding rituals (1992), Maillochon shows that the decline of marriage is associated with a renewed and diversified set of rituals, ensuring that its normative character remains intact. The ‘personalization’ of marriage is the latest expression of its conformism. Expanding on earlier findings based on surveys of sexual behaviour (The Context of Sexuality in France [Contexte de la sexualité en France], INSERM–INED, 2005–2006) and the Family and Housing survey (Famille et logements, INSEE, 2011), Rault and Lambert examine how conjugal and sexual relationships with same-sex partners are reported now that marriage has been opened to gay and lesbian couples. While reporting has been increasing steadily for several decades, it remains socially situated.

5While each article addresses a separate theme and applies specific methods, they are all linked by some common threads. The first concerns relationship norms. Individual trajectories are, of course, increasingly marked by separations, repartnering, and ever more diverse forms of union, as several of the articles point out. The conjugal norm has nonetheless tended to strengthen rather than weaken; it is as if the diversification of union forms—through the recognition of same-sex couples, non-cohabiting unions, and non-marital relationships, etc.—has rendered conjugal life all the more compelling. New lines are being drawn. There is no longer just one legitimate form of union, as was the case during the first French survey on union formation in 1959, designed by Alain Girard (1964), when non-marital births, consensual unions, and same-sex relationships were socially condemned. Yet, the most socially expected private living arrangement remains that of the couple. Living without a partner, even by choice, remains socially discredited, while multipartner arrangements (not covered here) appear to be more of a media phenomenon than a genuine and deep-rooted trend.

6Gender is a second common thread. It continues to shape conjugality while also being its product, be it in marriage, whose ritual is an ongoing reminder of the gender order; in repartnering, less frequent among mothers than fathers; in changes in work-related gender disparities, within couples, that tend to favour men; in singlehood, experienced differently by men and women; or in same-sex conjugal or sexual relationships.

7This issue offers a first view onto the research avenues opened up by the EPIC survey. Several studies have already been published. They concern first unions (Rault and Régnier-Loilier, 2015), online dating (Bergström, 2016a, 2016b, 2018), conjugal and family trajectories depending on social background (Costemalle, 2015), engagement (Rault, 2018), the seasonality of cohabiting union formation (Breton et al., 2018), and the PACS civil partnership (Rault, 2019). Further articles are in preparation, covering a wide range of topics, notably on core themes of the two previous surveys on union formation (1959 and 1983–1984), such as meeting places and criteria used to judge potential partners. The research based on these three surveys will make it possible to measure and document a century of union formation in France.