What does it mean to be and become an American? At least three answers to this question exist in the American political thought literature. First, the universal account emphasizes attachment to the universal political principles contained in the American Creed. Second, the cultural hypothesis affirms America's distinctly Anglo-Protestant political, cultural, and religious traditions. Finally, the civic formulation argues that Americans are defined by civic participation and the public virtue necessary for self-governance. All of these interpretations must respond to two challenges. The first denies the existence of a single, overarching understanding of "American-ness" and the second suggests that being an American is best understood in commercial terms.