Summary/Abstract This project will expand and improve the IPUMS Multigenerational Longitudinal Panel (MLP), the world’s largest longitudinal population data system. MLP currently includes linked censuses from 1850 through 1940, administrative records from Social Security, selected vital records, and links between several surveys of aging and the 1940 census. We propose to multiply the analytic power of MLP by expanding it and making it easily interoperable with other sources of linked data. Under our proposed Aims, MLP will be expanded to include all available records from the 1950 decennial census, new death certificate data, additional linkages to surveys of aging, and rich data on health outcomes. To make this massive infrastructure sustainable and accessible, we also propose refinement of software and methods for automatic record linkage, maintenance of the system of linked records, and dissemination of linked data. The expanded and improved MLP will provide the most comprehensive view of long-run changes in life-course dynamics available for any place in the world and will transform our understanding of processes of population aging. MLP is a highly cost-effective use of scarce resources to develop shared infrastructure for research, education, and policy-making on health and aging. The longitudinal panel will reduce redundant effort by researchers, increase data quality, and improve replicability and comparability. The proposed work is directly relevant to the core mission of the Population and Social Processes branch of NIA: The new data will advance fundamental knowledge about the causes and consequences of changes in social, demographic, economic, and health characteristics of the older population in the U.S. and will support research on the effects of public policies, social institutions, and environmental conditions on the health, cognition, well-being, and functioning of people, both over the life course and in their later years.