Financial resources are known to affect health outcomes. Many types of social policies and programs, including social assistance and social insurance, have been implemented around the world to increase financial resources. We refer to these as cash transfers. In this article, we discuss theory and evidence on whether, how, for whom, and to what extent purposeful cash transfers improve health. Evidence suggests that cash transfers produce positive health effects, but there are many complexities and variations in the outcomes. Continuing research and policy innovation—for example, universal basic income and universal Child Development Accounts—are likely to be productive.