Coresidence is of enduring importance across an individual’s life and a recurring feature of kinship. Most individuals will live with at least one person related to them through biological or legal ties for a majority of their lives. Given that demographic processes, social change, and economic development during the 20th century have resulted in increasingly diverse families, along economic, race/ethnic, geographic, and cultural lines, studying coresidence among contemporary American families is crucial. This research will inform the development of social and economic policies for the well-being of an increasingly heterogeneous American population. In this dissertation, I expand our current understanding of kinship relationships by studying coresidence among diverse American families. Recognizing that the prevalence of coresidence and the individuals with whom one lives will vary by life stage, I take a life course approach, studying coresidence at different developmental stages: middle childhood (Chapter 1), young adulthood (Chapter 2), and late middle-age (Chapter 3). Moreover, I build on the foci of prior work at each developmental stage, but shift attention to the aspects of households and families that are of particular relevance today: multigenerational households and immigrant families, the role of geographic opportunities and constraints in becoming residentially independent, and racial differences in support to aging parents. Across the three chapters, the results underscore the reliance on family members for help. Thus, variations in living arrangements are reflective of the hardships distributed unevenly across the population that contribute to the growing economic inequality characterizing the United States. Given that large swaths of the American population continue to experience financial insecurity, this research may inform the development of social and economic policies for the well-being of an increasingly heterogeneous American population.