The United States has never had an established religion, but by the early twentieth century many Episcopalians had come to think of themselves as the nation’s religious establishment. No other denomination, they believed, was as well-suited to provide moral leadership for the nation and unite its people in faith. This article argues that their commitment to a national civic mission provided Episcopalians with a sense of collective purpose that diverted attention from internal divisions and helped propel the church to a position of prominence within American religious life. It also reveals how many of the prime proponents and beneficiaries of the church’s ascendancy were members of the social and financial elite. Committed to a patrician creed of social responsibility, these “representatives of all that is noble” gained status and moral authority through their public support of the church and its mission. To trace the contours of the Episcopal ascendancy, this article focuses on developments within the Diocese of Pennsylvania, one of the largest, wealthiest, and most influential within the church. Over the course of the early twentieth century, its members overcame their prevailing parochialism, strengthened their denominational identity, and brought their influence to bear on the nation’s religious life. Their exercise of religious and cultural authority can be seen in their support of three ecclesiastical projects—the proposed diocesan cathedral, historic Christ Church, and the Washington Memorial Chapel at Valley Forge—which helped fashion the public image of the Episcopal Church as the nation’s religious establishment.