The research article's authors argue that support for parties of the radical right and left can usefully be understood as a problem of social integration—an approach that brings together economic and cultural explanations for populism. With comparative survey data, they assess whether support for parties of the radical right and left is associated with feelings of social marginalization. They find that people who feel more socially marginal—because they lack strong attachment to the normative order, social engagement, or a sense of social respect—are more likely to be alienated from mainstream politics and to support radical parties. They also find an association between indicators for recent economic and cultural developments often said to affect social status and feelings of social marginalization, especially among people with low incomes or educational attainment. They conclude that problems of social integration and subjective social status deserve more attention from scholars of comparative political behavior.