Objective: The objective of this study was to examine how young people in Nairobi, Kenya, are making sense of marriage, both in terms of their own lives and its social significance. Background: In many sub-Saharan African communities, marriage has been a fundamental marker of the transition to adulthood. However, union formation is changing, particularly in urban areas—partnering is occurring later and nonmarital cohabitation is increasingly common with the pathways to union formation differing by gender. Young people's perspectives on marriage are valuable for a deeper understanding of these trends. Method: A total of 74 in-depth interviews with youth living in the slums of Nairobi, Kenya, were qualitatively analyzed with particular attention to personal and normative understandings of marriage along with how they vary by gender. Results: Marriage emerged as an important part of most respondents' life projects, whether or not they considered it key to socially recognized adulthood. Attitudes differed by gender, with young women's greater ambivalence and aversion toward marriage, particularly early marriage, contrasting with young men's frustrated desire for marriage amidst economic constraints. Young men's main worry about marriage was not being able to support a family, whereas young women were often concerned that marrying would thwart their aspirations regarding education and work. Conclusion: Marriage continues to be a significant social marker of adulthood despite a shifting demographic reality. Differences in young people's attitudes are related to gendered concerns around marriage and economic independence.