This Article explores the optimal level of income redistribution by examining the potential welfare gains from redistributive tax and spending policies. Drawing on recent research on human happiness, this Article argues that while wealthy nations are generally happier than their poorer counterparts, neither national nor individual economic growth appear to have an appreciable impact on the subjective well-being of the citizens of relatively wealthy nations. Significant causes of this finding include the problem of rivalry—that increases in the income of some depress the happiness of others—and the fact that individuals overestimate the degree to which additional consumption will improve their happiness. Studies show the level of inequality in a society also may affect levels of happiness. Ultimately, happiness research is consistent with the strongest justification for adopting a progressive tax structure--income has declining marginal utility thus redistribution can increase total welfare in a society.