The Social Bases of Political Parties: A New Measure and Survey

This article proposes a measure of the social structuration of political parties. The measure has some distinctive virtues. It assesses the social bases of partisanship from the standpoint of the political party, and it provides a simple and transparent method for assessing the relative weight of social-structural and behavioral factors for party composition. We illustrate the power of this measure through a comparison of political parties in 30 European countries since 1975.