1. IntroductionAlthough marriage remains almost universal in sub-Saharan Africa, there have been widespread and profound changes in the transition to marriage across the region over the last few decades (Lloyd 2005; Marcoux and Antoine 2014). Even in West Africa, where a large proportion of still marry early, in most countries the median age of first marriage among and, to a lesser extent, among men has consistently risen since the end of the 1970s, especially in urban areas (Hertrich 2007; Tabutin and Schoumaker 2004). Not only are first marriages postponed, but the process of formation is also changing in many African cities, including Ouagadougou. One of the noticeable changes in the Burkinabe capital city is the rising prevalence of consensual unions among youth, who choose to cohabit with a partner without performing any marriage ceremony (Calves, Kobiane, and Martel 2007; Legrand and Younoussi 2009). Today, unmarried cohabitation seems less stigmatized than in the past, and what used to be commonly regarded by Burkinabe city dwellers as a clear transgression of the rules is increasingly emerging as a tolerated form of intermediary conjugal union (Attane 2007).Despite the growing popularity of unmarried cohabitation among youth in several African cities, and even though the rise of cohabitating unions has become a policy issue and the subject of heated public debate in some countries (Mokomane 2005a; Posel, Rudwick, and Casale 2011; Bocquier and Khasakhala 2009), cohabitation behavior is rarely studied in sub-Saharan Africa and the choice between marriage and cohabitation in the region still attracts little attention when compared to other parts of the world. In fact, unmarried cohabitation and marriage are still often treated as synonymous by Africanist demographers, who tend to group cohabiting and married under the general label women in union. This lack of distinction is problematic, however, as the increasing prevalence of unmarried cohabitation, even as a prelude to formal marriage, may reflect not only larger social changes such as the emergence of new values and expectations among the young generation of African city dwellers with respect to partnership and family (Werner 2006; Cole and Thomas 2009) but may also have important implications for and their children.In fact, despite its postponement, formal marriage still constitutes an essential source of social status for in Burkina Faso and remains crucial to their securing access to money, housing, and land (Bardem and Gobatto 1995; Rossier 2007; Roth 2010). Unlike their married counterparts, unmarried cohabiting also lack legal and social protection when the relationship ends. As for children born within unmarried relations, their social identity and access to wealth and inheritance depend on their biological father's willingness to acknowledge paternity and support them. Scattered evidence suggests that an increasing number of young fathers in Burkinabe cities fail to do so (Mazzocchetti 2007; Carle and Bonnet 2009).In such a context, exploring the rising phenomenon of young unmarried cohabiting couples and factors affecting the choice between marriage and unmarried cohabitation among urban youth becomes all the more salient. Based on unique life history data, including biographies of relationships recently collected among young adults, the study takes a competing risks approach to examine relationship transitions to a first marriage or an unmarried cohabitating in Ouagadougou, the capital city of Burkina Faso. The nature of the data allows us to go beyond the traditional one-sided analysis of formation, focusing on either men or women, and evaluate how characteristics of both partners involved in a dating relationship affect the choice between marriage and nonmarital cohabitation when forming a first union.2. Background and hypotheses2.1 Rising unmarried cohabitation in urban AfricaFor a long time, marriage in sub-Saharan Africa occurred early and was universal, but since the end of 1970s most countries in the region have been moving into a new phase marked by a consistent rise in women's age at first marriage, especially in urban areas (Tabutin and Schoumaker 2004; Hertrich 2007). …