The class cleavage has been the most important structuring force in most West European countries. In the last decades, the question regarding whether the social class still influences voting behavior has been intensively debated. One strand of literature suggests a transformation of the old class divide into a new – or reformulated – class cleavage. However, there is still little empirical evidence about the circumstances under which this new divide may become important. The present paper contributes to fill this gap, by analyzing in how far electoral competition conditions the strength of the new class cleavage. Applying data from the Swiss National Elections 2007 and 2011 to a comparative analysis across cantons we find that the impact of the new class cleavage on electoral choice varies according to party system polarization. The proportionality of the electoral system, by contrast, does not have a clear conditional effect.