PATH commissioned this report in an effort to evaluate whether dose-sparing, possibly through the intradermal (ID) route, could improve the availability of yellow fever vaccine globally. The authors identify and discuss potential benefits, possible obstacles, and associated costs of dose-sparing as a vaccine delivery strategy. In addition, the report includes an assessment of which settings would be most appropriate and to what extent novel ID delivery devices, such as needle-free disposable-syringe jet injectors, would help to facilitate its successful implementation.