The failure of mainstream political-party competition fueled the rise of populism in Europe. Popular anxieties about immigration, economics, or cultural change are not sufficient to explain the surge in populist support. Mainstream parties on both the center-left and the center-right have failed to represent constituencies, to articulate their needs, and to propose distinct policy solutions. The center-left has abandoned its traditional social-policy commitments, and the center-right has often failed to contain xenophobes and nativists. For voters, these failures validated populist claims that the political status quo amounted to rule by a corrupt, self-serving elite cartel and that only radical solutions could ensure real representation of “the people.”