Adam Sheingate has made an important contribution to the literature on political entrepreneurship. He takes a concept that has been widely but casually employed by political scientists studying institutions and policies and sets out to supply that concept with clarity and content. Appropriating the concept for historical institutionalism, he connects the role of the political entrepreneur to the processes of institutional change, posing a powerful challenge to the familiar view of institutions in equilibrium. Especially important for readers of this journal, he expands upon previous uses of the concept by arguing that it offers a new vantage point on American political development, with political entrepreneurs posited to be critical sources of endogenous change.