American Jewish liberalism fascinates me because it contradicts nearly everything I was taught about why people vote as they do. If economic self-interest largely drives voting choices, why for nearly a century has this affluent population favored the more liberal political party? In trying to solve this puzzle, I realized that conventional explanations based on Judaic factors are inadequate. If something intrinsic to Judaism is responsible for Jewish liberalism, why are American Jews the only diaspora community still on the left side of their nation’s political spectrum and why does their attachment to liberalism fluctuate over time? These insights helped me realize that American Jews are disproportionately attracted to political liberalism because they are American Jews for whom the liberal design of the American polity has offered full citizenship and political opportunities unavailable elsewhere.