Over the past twenty years, Gavi, the Vaccine Alliance, has proven to be a high-impact and resilient global health partnership. Launched at the World Economic Forum in Davos in 2000, Gavi has mobilized its network of government, private sector, and civil society partners to make vaccines affordable and available to millions of children in the world’s lowest-income countries. Yet after years of improvements, immunization coverage has now stagnated in some countries, and the challenges posed by demographic change, urbanization, and conflict all threaten to slow global progress. Gavi’s new strategy for 2021-2025 lays out a plan to confront these challenges and reach the most vulnerable children with vaccines, and the organization will seek funding to help it reach its goals at a pledging conference to be hosted by the United Kingdom in June of 2020. The United States has supported Gavi since 2000, and the Alliance’s contributions to health security and efforts to enable countries to move towards sustainable, self-financed immunization programs resonate with U.S. global health and development goals.