In the context of population aging and changing families, it is pressing to understand whether there will be sufficient care resources to meet the growing care needs of older adults. This dissertation contributes to the discussion of who will care for older adults in aging societies through three essays that examine the dynamics and inequalities of care resources embedded in later-life social ties. Chapter 1 takes a first step toward understanding the transition from potential care networks to actual care networks at the onset of care needs, as well as its implications for unmet care needs. Leveraging the longitudinal data from the National Health and Aging Trends Study (NHATS) 2011-2019, I find that among all potential caregivers, those who have already supported older adults in some ways are more likely to be activated as actual caregivers, and multiplex helpers (providing both emotional and instrumental support) are most likely to be activated. Having multiplex helpers activated as caregivers is associated with a significantly lower rate of unmet care needs. This study advances our understanding of the formation of care networks and provides important policy implications for how to better meet the increasing care needs of older adults in aging societies. Chapter 2 provides the first comprehensive description of turnover in care networks based on the longitudinal analysis with NHATS 2011-2019 data. Results suggest that turnover in care networks is prevalent, with more than half of care recipients having ever experienced any turnover in their care networks in just a one-year time frame. Women, non-Hispanic Black, and Hispanic older adults are significantly more likely to experience care network turnover, even after accounting for life course transitions such as changes in marital status, employment status, and health status. Older adults who experienced the substitution of caregivers (both losing previous caregivers and adding new caregivers) tend to report more unmet care needs. Understanding these patterns can be helpful for policymakers and practitioners to design effective programs to manage the turnover of caregivers and improve the quality of care received by older adults across diverse social groups. Chapter 3 (coauthored with Adriana Reyes) examines how access to care resources shapes intercounty moving decisions of older adults. Merging the geocoded data from the Health and Retirement Study (HRS) 2004-2018 with the county-level care resources (the relative availability of nursing home beds and home health agencies) extracted from the LTCFocus database, we find that older adults without any adult children within 30 miles or living in counties with limited long-term care resources are more likely to initiate intercounty moves. Intercounty movers tend to move to counties closer to their adult children but may not necessarily settle in counties with more formal care resources. These results underscore the potential importance of access to care resources in shaping the intercounty moving decisions of older adults. State and local policymakers should be aware of the growing care needs of older migrants and build care-sufficient environments that enable older adults to age in the right place.