Global trends in the rich world, filtered through America’s unique two-party system, have transformed each party’s coalition and reinforced contrasting views of expertise. Although the rise of social issues and the rising importance of education are transnational, they raise unique challenges for each major American party. Each side has responded by shifting its agenda and public image. Democratic politicians have balanced their instinctive reluctance to alienate culturally traditionalist voting blocs against internal pressure from party members for a socially progressive, intellectually erudite, and demographically diverse party leadership. Republicans have been compelled to defer to a popular conservative media apparatus that promotes aversion to social transformation and hostility to claims of expertise by nonconservative authorities. Barack Obama (the wonky advocate of social change) and Donald Trump (the plain-spoken, nostalgic nemesis of experts) both personify their respective parties. These party leaders repel as well as attract, reinforcing our two-sided politics.