Facing globalization, the challenge for political science resembles that of the founders of the United States: how to design institutions for a polity of unprecedented size and diversity. Globalization produces discord and requires effective governance, but effective institutions are difficult to create and maintain. Liberal-democratic institutions must also meet standards of accountability and participation, and should foster persuasion rather than rely on coercion and interest-based bargaining. Effective institutions must rely on self-interest rather than altruism, yet both liberal-democratic legitimacy and the meaning of self-interest depend on people’s values and beliefs. The analysis of beliefs, and their effect on institutional outcomes, must therefore be integrated into institutional analysis. Insights from branches of political science as diverse as game theory, rational-choice institutionalism, historical institutionalism, and democratic theory can help political scientists understand how to design institutions on a world—and human—scale.