This thesis studies the rise of national conservatism, a new conservative movement that has gained prominence since the election of President Donald J. Trump. National conservatives oppose the liberal international order, seeking to restore the primacy of the nation-state and fully reject liberalism. National conservatism is not populist but rather a movement within elite conservative circles. It hopes to fully dislodge neoconservative, neoliberal, and libertarian ideas from the Republican Party. The three core issues that national conservatives seek to promote are restrictive trade policy, limited immigration, and a neo-isolationist foreign policy. Figures like Yoram Hazony, Tucker Carlson, Peter Thiel, Josh Hawley, and Adrian Vermeule are associated with national conservatism. National conservatives stand to exert significant influence on the future of the Republican Party, American politics, and the liberal international order. This thesis presents a history of the Republican Party after the Cold War and an analysis of the theory and political economy of national conservatism.