Returning to forgotten themes in the Federalist Papers, the article argues that the state and federal governments compete with one another for the “affection” of their citizens and for the regulatory power that often accompanies that affection. The article further contends that citizens and politicians are able fully to participate in this affection-driven marketplace only if three prerequisites are met: each sovereign must be assured of an opportunity to demonstrate its competence; each sovereign must enjoy a significant measure of autonomy from the other; and the two sovereigns’ dealings with one another must be sufficiently transparent to enable citizens to allocate praise and blame in an accurate fashion. The article then argues that, although the Court has not characterized its federalism rulings in this way, and although one may question whether the judiciary is ultimately competent to play an ongoing, prominent role in preserving the marketplace’s vitality, the Court appears determined to ensure that these three market requirements are satisfied. The article concludes by urging courts and scholars to consider the ways in which the marketplace’s health may best be preserved and the ways in which a broad range of legal doctrines and law-making practices frustrate or advance federalism’s forgotten objective of competition between the two sovereigns.