With ongoing changes in mortality and fertility, numerous social challenges have accompanied population aging. This dissertation draws on data from the United States and the United Kingdom to examine the social dimensions of family and care in the context of population aging. In the first chapter, I use data from the UK Household Longitudinal Study to explore differences in intergenerational co-residency between UK-born and foreign-born adults. I find that immigrants, regardless of age at migration, are less likely to co-reside with parents than UK-born individuals, suggesting structural barriers to migration and kin availability shape multigenerational household formation, with implications for family care. In the second chapter, I use data from the Survey of Income and Program Participation (SIPP) to examine the personal care needs and care arrangements of individuals 65 and older living in the United States, focusing on how life stage at migration impacts aging-related care. I find that immigrants who migrate to the United States after age 50 show distinct care needs and care arrangements, likely driven by barriers to health and retirement supports. In chapter three, I use data from the SIPP to explore the relationship between unpaid caregiving and women’s labor market participation in the context of changing demographics of care. Given patterns of population longevity and later ages of childbearing, more individuals are exposed to overlapping child and adult care responsibilities across the life course. I examine connections between “sandwich caregiving” and labor market participation among women living in the United States and find that sandwich caregivers who are younger, caring for young children, and providing “high intensity” adult care face the largest labor market penalties. I discuss these findings against the backdrop of eroding social supports for both child and adult care. My dissertation presents new evidence aimed at exposing the fragility of existing safety-nets for long-term care, and I argue that, without a critical examination of social policies and practices that organize long-term care, population aging will continue to exacerbate inequalities by gender, race, and immigrant status.