This chapter reviews research on social and political cleavages and how they influence political participation. Starting with the general debate on the role of cleavages in contemporary politics, some of the most important contributions in the research literature are discussed. Scholars of political participation, it is then shown, have used the cleavage concept but have focussed primarily on specific modes such as turnout and have mostly explored social cleavages. Interpreting cleavages—or political cleavages—as a contextual factor, by contrast, has been used above all by research into protest politics. In addition to the review of extant research, an exploratory analysis shows how demographic characteristics and values associated with old and new cleavages affect various modes of participation throughout Europe.