Project Summary/Abstract Kinship ties form the bedrock of societies and provide meaning in terms of roles, obligations, and responsi- bilities. Generational overlap in the form of shared lifetimes represents a fundamental condition guiding whether and how kin relationships may develop and the extent to which resources are shared. Yet, we know little about the prevalence, duration, or life course timing of generational overlap, how it varies by socioeco- nomic status, and how it may potentially influence individual health and wellbeing. Generational overlap is con- sequential because it offers an important perspective for observing the demographic constraints on multigener- ational family investments in children. We propose to provide new information about the overlap in shared life- times for grandchildren and grandparents across two industrialized countries – the U.S. and Denmark. Both countries have experienced declines and delays in fertility, lengthening life expectancies, and notable educa- tional expansion in the 20th century, but these have occurred on different timelines, to different degrees, and within different social policy regimes. We use harmonized data from the Panel Study of Income Dynamics, the Danish population register, the Add Health Parent Study and the Survey of Health, Aging, and Retirement in Europe to evaluate generational overlap and its implications across historical time. We consider three genera- tions – grandparents (G1), parents (G2), and grandchildren (G3) and focus on grandparents born since 1912. We address three specific aims: 1) Provide a descriptive portrait of the prevalence and length of generational overlap for grandparents (G1) and grandchildren (G3) in the U.S. and Denmark using an innovative age-pe- riod-cohort approach; 2) Explicate the role of educational expansion in shifting generational overlap, including the specific case of within-family intergenerational mobility where diminished generational overlap may be an unanticipated `cost' of intergenerational mobility; 3) Document the social class gradient in grandparents' life course position (employment status, health, and proximity to kin) arising from the timing and duration of gener- ational overlap and describe the intergenerational exchanges of time, money, and care that result – and for Denmark, consider subsequent health/wellbeing for G1-G3. We attend to further variation by gender, family structure, and (for the U.S.) race/ethnicity. In sum, shared lifetimes among grandparents, parents and grand- children represent a key aspect of how kinship ties shape individual life courses. We explore how the duration, quality, and consequences of these shared lifetimes are shaped by demographic processes across genera- tions. This project will be led by an outstanding team of established collaborators who are leaders in the fields of family demography and social inequality and who possess the methodological skill and expert knowledge of each data source t...