This paper argues that we need to bring social theory back in to gain a better understanding of current democratic conflicts. In recent years, the “new cleavage” argument has gained considerable attention among political scientists and a wider public. It states that a new cleavage increasingly splits the social and political landscapes into cosmopolites and communitarians, defenders and discoverers, winners and losers of modernization. In contrast to the new cleavage argument, however, cleavage theory was originally derived from an intricate discussion of social theory and an elaborated theory of modernity. I propose that we need to bring social theory back in. After revisiting Lipset's & Rokkan's argument that the rise of modernity produced long-lasting political cleavages, I will draw on sociological research about the structural transformation of modernity in order to explore their impact on contemporary cleavage structures. In sum, the paper presents a systematic approach to revising cleavage theory.