This article focuses on new democracies in Eastern Europe and addresses two questions about the translation of social cleavages into political oppositions. The first question concerns the translation of preexisting cleavages: does the evolution of new party systems influence the politicization of social conflicts? The second question concerns the translation of new social cleavages, that is, cleavages that emerge once a party system freezes: can a new social cleavage be politicized? To answer these questions, the article integrates a formalization of social cleavage theory with a game-theoretic model of a new party system. The first result is that translation of preexisting cleavages depends on which parties survive the early rounds of electoral competition. In fact, depending on which parties survive, the axis of political conflict can shift by 90 degrees. This implies that party systems in new democracies should be seen as important founding moments, during which political actors determine the long-term axes of political conflict. The second result is that once a party system freezes, the politicization of a new social cleavage is difficult. Indeed, it is possible that a new social cleavage will remain politically dormant. In the context of Eastern Europe, this result suggests that political salience of class conflict is likely to be low because competitive elections and political parties predate the entrenchment of property-owning classes.