The authors revisit the core questions of public finance, armed with a richer perspective on human behavior. They do not merely apply findings from psychology to specific economic problems; instead, they explore how psychological factors actually reshape core concepts in public finance such as moral hazard, deadweight loss, and incentives. Part one sets the stage for integrating behavioral economics into public finance by interpreting the evidence from psychology and developing a framework for applying it to questions in public finance. In part two, the authors apply that framework to specific topics in public finance, including social insurance, externalities and public goods, income support and redistribution, and taxation. In doing so, the authors build a unified analytical approach that encompasses both traditional policy levers, such as taxes and subsidies, and more psychologically informed instruments. The net result of this innovative approach is a fully behavioral public finance, an integration of psychology and the economics of the public sector that is explicit, systematic, rigorous, and realistic.