The 21st Century Cures Act permitted people with end-stage renal disease (ESRD) to enroll in Medicare Advantage (MA) effective January 2021. It is imperative to understand the breadth of dialysis facility networks across MA contracts because most patients with ESRD need thrice-weekly dialysis to survive. In 2020 MA contracts' networks included a mean of 51 percent of dialysis facilities in their service areas. MA contracts with plans in a single state, with not-for-profit status, and with higher proportions of dually eligible enrollees with ESRD were significantly more likely to include less than or equal to 25 percent of dialysis facilities in their service area in network ("narrow networks") than contracts with plans in multiple states, with for-profit status, and with lower proportions of dually eligible enrollees with ESRD (by 12.9, 13.0, and 11.7 percentage points, respectively). Hispanic, Asian/Pacific Islander, and American Indian/Alaska Native people with ESRD were enrolled in contracts with narrow networks of dialysis facilities at markedly higher rates than non-Hispanic White people with ESRD. In contrast, Black people with ESRD were less likely to be enrolled in a narrow-network contract. Policy makers should monitor and address the adequacy of dialysis facility networks in MA contracts, as well as disparities in enrollment in narrow-network plans.