The Health and Retirement Study (HRS) is the largest national panel study of Americans over age 50. Supported by the National Institute on Aging (NIA U01AG009740) and the Social Security Administration, the HRS provides decades of cutting-edge, free publicly available data on aging, supporting research, policy, and innovation to address the challenges of a rapidly aging population. In addition to core survey content on health and health insurance, employment and retirement, income and wealth, and family connections, HRS data includes psychosocial functioning, genetics, physical performance, and venous blood for biomarkers. Additionally, the HRS survey data are linked to external sources of information from Social Security, Medicare and Medicaid, Veteran’s Affairs, the National Death Index, employer-provided pension plans, and contextual data. HRS has also contributed to building an infrastructure for cross national comparisons by serving as the model for a network of studies of aging around the world with harmonized content. The HRS’ Harmonized Cognitive Assessment Protocol (HCAP) leverages that infrastructure, collaborating and harmonizing with multiple international partners to establish an international data resource to better understand and compare the causes, consequences, and trends in dementia in the U.S. and around the world. HRS data serves as the foundation for thousands of peer-reviewed journal articles and reports, as well as hundreds of Master’s theses, PhD dissertations, and books.