There are two ways to answer the question, What can Catholic social thought learn from the social sciences about the common good? A more modern form of Catholic social thought, which primarily thinks of the common good in terms of the equitable distribution of goods like health, education, and opportunity, could benefit from the extensive literature in public policy, economics, and political science, which study the role of institutions and policies in generating desirable social outcomes. A second approach, rooted in pre-Machiavellian Catholic thought, would expand on this modern notion to include concerns about the way the culture shapes our understanding of what genuine human flourishing entails. On that account, the social sciences offer a valuable description of human life; but because they underestimate how human behavior is shaped by institutions, policies, and the discourse of social science itself, their insights need to be treated with caution.