In the wake of the October 1929 stock market crash, conservatives formed an array of organizations and publications that aimed to resist the nation’s steady embrace of New Deal liberalism. Crucial to their opposition was a group of “nationalist conservatives” whose most prominent member was the operative and propagandist Merwin K. Hart. Hart’s worldview, which embraced nativism, antisemitism, anti-interventionism, and economic libertarianism, was shared by a range of figures on the right whose contributions to the emergence of the postwar conservative movement have not been studied. Hart’s organization, the New York State Economic Council (later renamed the National Economic Council), played a critical function in propagating conservative ideas throughout the years of liberal political hegemony. Scholarship on conservatism has generally cast the early opponents of the New Deal as principled libertarians, unsullied by bigotry and nativism; this article challenges that picture, arguing that the nationalist conservatives were critical in shaping the ideology of the postwar right.