This report started with a simple question—“How can we tell how much funding is devoted to global health programs?”—and ended (more than two years later) with an answer that is far from simple. As those who have tried know well, tracking health-related funding is challenging in any setting, given the range of public and private sources and the many types of services and programs that fall within the definition of “health sector.” It is made all the more complicated when significant external support from donors and private charities plus in-kind donations of drugs and other inputs are taken into account. The task is made yet harder by inadequate public expenditure management systems in countries where public agencies’ capacity is stretched very thin and by donor accounting structures that are not designed to respond in a timely way