Abstract: Why does the American Constitution lack certain social and economic guarantees, which appear in most contemporary constitutions? This essay explores four possible answers: chronological, cultural, institutional, and realist. The chronological explanation emphasizes the fact that in the late eighteenth century, social and economic rights simply were not on the viewscreen for constitution-makers. The point is correct, but as a complete account, the chronological explanation fails for the simple reason that constitutional meaning changes over time. The institutional explanation emphasizes that Americans typically see constitutional rights not as mere goals or aspirations, but as pragmatic instruments for judicial enforcement. The difficulty with the institutional explanation is that social and economic rights can, in fact, be enforced judicially. The cultural explanation sees the absence of social and economic rights as part of the general failure of socialist movements in the United States ("American exceptionalism"). The problem with this explanation is that social and economic rights can in fact coexist with a market economy. The realist explanation places a spotlight on the underappreciated fact that the United States Supreme Court came very close, in the 1960s and 1970s, to recognizing social and economic rights under the Constitution. The Court's refusal to recognize such rights was largely a result of the presidential election of 1968 and in particular of four critical appointments by President Nixon. This is an important source of "American exceptionalism" in the domain of social and economic rights. Here as elsewhere, there is a possibility of multiple equilibria, and with a small difference or two, the United States might well have had an equilibrium that included social and economic rights.