Before the advent of democratic rule in South Africa, most people had expected the country to experience an explosion of politicized ethnicity when minority rule was replaced. Yet this has not come to pass, and ethnic political parties have declined in number and influence in post-apartheid South Africa. Instead, between 1994 and 1999 partisan politics developed in a multipolar direction, with some parties embracing racial mobilization and others attempting to build multi-ethnic, non-racial entities. This article explains these developments as a product of the ways that political parties have responded to the incentives established by political institutions, on the one hand, and the structure of social divisions, on the other. The analysis holds implications for our understanding of the ways in which social cleavages in ethnically divided societies become politically salient, and for the lessons of institutional and constitutional engineering, particularly with respect to how proportional representation systems interact with other factors to shape politics in ethnically diverse societies.