This book addresses a range of relevant theoretical issues, including the possibility of an interpersonally comparable measure of well-being, or “utility” metric; the moral value of equality, and how that bears on the form of the social welfare function; social choice under uncertainty; and the possibility of integrating considerations of individual choice and responsibility into the social-welfare-function framework. This book also deals with issues of implementation, and explores how survey data and other sources of evidence might be used to calibrate both a utility metric and a social welfare function, and whether distributive goals are ever best pursued through regulation rather than the tax system. In working through this range of theoretical and practical issues, the book draws from a wide variety of literatures, including philosophical scholarship on equality, responsibility, the nature of well-being, and personal identity over time; the social choice literature within economics; applied economic literatures concerning the measurement of inequality and poverty; legal and policy-analysis scholarship on cost-benefit analysis, environmental justice, and the choice between regulation and taxation; and the burgeoning field of “happiness studies”.