Entering a cohabiting union, getting married, and/or having children are all considered defining features of the transition to adulthood. Life course research has shown that contemporary youth are taking longer to achieve these traditional milestones and are showing increased variability in completing these transitions. To better theorize this heterogeneity, this article draws on theories of purposive action to conceptualize agency in family formation and suggests turning to critical scholarship to link family formation in emerging adulthood to broader patterns of social inequality. Carefully theorizing gender in the context of linked lives also enables an understanding of how coordinated family behaviors among heterosexual couples can produce variability within and across families and ultimately challenge or reproduce gender inequality. A conceptual framework for gendered projectivity and linked lives is proposed as an example of how to expand life course thinking.