Accurate, complete, and appropriately detailed race and ethnicity data for Medicare beneficiaries are critical to identifying and mitigating health disparities. As racial and ethnic disparities have emerged among those impacted by COVID-19, the availability and quality of data on race and ethnicity has garnered greater attention and scrutiny. This study will describe the extent to which Medicare's race and ethnicity data for beneficiaries are complete and accurate. We will compare these data to data from other sources. We will also determine the extent to which the Medicare beneficiary race and ethnicity data align with Federal data standards.