Led by JSI, Gavi’s Zero-Dose Learning Hub (ZDLH) is a global learning initiative that supports country-led efforts to generate evidence and engage stakeholders to identify and reach zero-dose and under-immunized children, helping to strengthen immunization programs and expand access to vaccination. This one-page document summarizes the ZDLH's core activities, including providing technical assistance to four Country Learning Hubs; synthesizing evidence for decision making; and maintaining a central, web-based repository of zero-dose data and evidence.