This article surveys the Presbyterian conflict in America at the turn of the twentieth century, which was marked by a drive for progress and a reaction of protest. After setting up the historical context, it looks at “progress” in action, theology, preaching, and presidents. It then focuses on the protest of J. Gresham Machen, who was engaged in church debates and publications (e.g., Christianity and Liberalism) and who, in response to progressive theology, founded Westminster Theological Seminary, an independent mission board, and a new denomination. It concludes with observations about the continuing witness of Westminster Seminary.