The vast majority of health research resources are used to study conditions that affect a small, advantaged portion of the global population. This distribution has been widely criticized as inequitable and threatens to exacerbate health disparities. However, there has been little systematic work on what individual health research funders ought to do in response. In this article, we analyze the general and special duties of research funders to the different populations that might benefit from health research. We assess how these duties apply to governmental, multilateral, nonprofit, and for-profit organizations. We thereby derive a framework for how different types of funders should take the beneficiaries of research into account when they allocate scarce research resources.