Project Summary The purpose of this application is to extend and enhance the National Health and Aging Trends Study (NHATS), a national platform for studying late life disability trends and trajectories. The overall aims of NHATS are to 1) promote scientific inquiry into late-life disability trends and dynamics, their antecedents and correlates, and disparities therein and (2) to advance study of the social and economic consequences of late-life disability for individuals, families, and society. To achieve these aims in the next five-year cycle, we will continue the unique key design features of NHATS including collecting data annually and in person from a nationally representative sample of older adults (sampled from the Medicare enrollment file) in 2019-2023 (Rounds 9-13). We will also add several innovative enhancements focused on objective measures of cognitive and sensory capacity and physical activity. Extending NHATS in this way will allow important scientific questions to be addressed concerning both shorter and longer-term in-depth trends in components of the disability process, as well as the dynamics of disability onset, progression and recovery. Specifically, in the next cycle NHATS will 1) Continue collection of the enhanced disability protocol and supplemental questions on disability antecedents and consequences including subjective and economic wellbeing, living and care arrangements, and quality of end of life; and replenish the sample in Round 10 (2020) in order to maintain NHATS' ability to produce 5-year age estimates (up to 90+) and Black-White comparisons; 2) Enrich and expand measurement in the NHATS' annual disability protocol including development and implementation of a) a new iPad-based protocol to enhance measures of cognitive and sensory capacity; and b) a panel substudy of physical activity using accelerometry; and 3) Document and disseminate NHATS data, make available linked claims files and new policy-relevant linkages, and provide new training opportunities to the growing NHATS user community. These aims will allow NHATS to achieve its overarching goal of providing a platform for scientific inquiry to guide efforts to reduce disability, maximize functioning, and enhance older adults' quality of life.