To what extent do the rules on state court personal jurisdiction distribute litigation to the forum that can resolve the dispute at the lowest social cost? It turns out that current rules do select the least-cost forum in many cases. However, three problems interfere with the goal of minimizing the costs of dispute resolution: (a) analysis under the Due Process Clause does not account for the full social costs of litigation, (b) federalism-based concerns sometimes allow state courts to adjudicate cases when they are not the most adequate forums, (c) institutional factors constrain the Supreme Court’s ability to prevent excessive exercises of state court jurisdiction. The dilemma of achieving forum efficiency within the existing legal and institutional framework helps to explain the confusion that pervades the Supreme Court’s state court personal jurisdiction cases.