Revisionist accounts conclude that divided and unified government do not differ significantly in the production of “important” public policy. I argue instead that when one theoretically reclaims the concerns about party responsiveness and institutional features of American politics that have animated party government scholars, unified government is significantly more productive than divided government. Employing a range of measures of important legislative enactments in the postwar period, I find that unified government produces greater quantities of significant enactments and is more responsive to the public mood than is divided government. The evidence suggests that parties do, as party government theorists maintain, generate incentives to cooperation that help transcend some of the policymaking gaps created by the Constitution.