Gavi, the Vaccine Alliance has provided over US$16 billion in funding for vaccination in low- and middle-income countries since 1999. We exploit differential timing across countries and vaccines to estimate the effects of this public health initiative. We find that Gavi’s support for a vaccine increased coverage rates by 2–5 percentage points across all vaccines and by 10–20 percentage points for newer vaccines. We also find that Gavi’s support reduced child mortality from related causes by 1 child per 1,000 live births. We estimate these improvements saved around 1.5 million lives at a cost of about US$9,000 per life saved. (JEL F35, F53, I12, I15, I18, J13, O15)