During the past thirty years in the social sciences, there has been a wide-ranging discussion of “class politics” in capitalist modernity. Several distinct threads have developed, largely in isolation from each other. The authors suggest that the various accounts implicitly rely on different definitions of class politics and propose a way to classify them. The classification is based on two questions: first, whether changes in the strength of the left depend on the working class specifically or on cross-class dynamics and, second, whether emergent class differences in politics are largely spontaneous or constructed. The authors use this classification to assess the prospects for testing the empirical implications of different accounts and point to the more general insights potentially offered by each approach.