PROJECT SUMMARY / ABSTRACT The Medicare Advantage (MA) program has experienced substantial growth over the last decade, particularly among racial/ethnic minorities. MA offers an alternative to traditional Medicare (TM) coverage by allowing Medicare beneficiaries to receive integrated medical and prescription drug coverage from private insurers. Although MA serves a growing population of Black and Hispanic beneficiaries, it remains unclear whether MA mitigates or exacerbates racial/ethnic disparities in care, as well as whether certain MA plans provide higher quality and more equitable care for Black and Hispanic enrollees than other MA plans. Rigorous evidence is needed to identify opportunities to reduce health care disparities in the Medicare program and design incentives for MA plans to improve care for Black and Hispanic enrollees. Thus, the overarching objectives of this study are to investigate whether enrollment in MA mitigates or exacerbates racial/ethnic disparities (i.e., between Black vs. white and Hispanic vs. white beneficiaries) in access, quality, and utilization of care relative to TM; to identify high-quality and high-equity MA plans; and to develop and validate measures of patient experiences with trust, discrimination, and equitable care that could be incorporated into future assessments of MA plan performance. We draw on rich sources of national data, including the Medicare Current Beneficiary Survey and encounter claims submitted by Medicare Advantage plans, and will also conduct a national survey of Medicare beneficiaries to assess experiences with trust, discrimination, and equity in care to evaluate disparities along different dimensions of care (access, quality, and patient experiences). We will go beyond existing surveys of the Medicare population by explicitly surveying beneficiaries about their experiences with equity, trust, and discrimination in care, and will provide evidence to guide how these items could be incorporated into future surveys of patient experiences and assessments of MA plan performance (e.g., plan star ratings). Thus, this project will illuminate how key features of the MA program overall, and attributes of particular MA plans, affect care for racial/ethnic minorities. It will also provide new evidence to inform how policymakers could take equity into account when evaluating the quality of MA plans, including assessing patient experiences with equitable vs. inequitable care. This work addresses NIA’s strategic priorities for 2020- 25 to identify health system factors underlying disparities and policy opportunities to reduce health care disparities among older adults. To enhance the impact of our work, we will disseminate findings through scientific publications and to a national network of policy stakeholders, including a Policy Advisory Committee comprised of experts in Medicare policy, the MA program, and disparities.