Initiated in 2013, the Gavi Full Country Evaluations (FCE) are 3-year prospective studies that aim to understand and quantify the barriers to and drivers of immunization program performance, with emphasis on the contribution of Gavi, the Vaccine Alliance in four countries: Bangladesh, Mozambique, Uganda, and Zambia. IHME is determining how Gavi’s process, products, and resources work at the country level to influence immunization-related outcomes.