Alberto Alesina and Edward Glaeser's recent book, Fighting Poverty in the US and Europe, exemplifies the recent incursion of economists into the domains of political science and sociology. In thinking about welfare states, economists have traditionally been interested in their effects on the distribution of income and, above all, their implications for efficiency and growth. Alesina and Glaeser instead set out to explain why the American welfare state is so small by comparison to European welfare states. This, then, is a book about American exceptionalism in the realm of social policy, but Alesina and Glaeser's discussion also addresses the general problem of accounting for cross-national variation in the public provision of social welfare. Their project is to provide an account of the exceptional nature of the American welfare state that is consistent with and sheds light on differences among other welfare states as well. This makes for an audacious book that deserves critical scrutiny.