In contrast with many other industrialized nations, communism has played a key role in French politics during the twentieth century. It has been especially significant in the life of the working class since 1920, having self-consciously and successfully made itself into a working-class party and often serving as the major voice of French workers in both national and local politics. Any social history of the French working class in the twentieth century must, therefore, take the French Communist Party (PCF) into account. Studies of the PCF's history, whether memoirs of Party members or more scholarly accounts, are certainly not in short supply. But for the most part, the historiography of French communism has focused on the activities of Party leaders and full-time militants, neglecting the study of the masses of French men and women who voted communist, without actively participating in or even belonging to the organization. Yet it was ultimately they, not the leadership, who gave the PCF its significance. Communist parties with leaders, committed militants, and squabbling factions have existed all over the world since the Russian Revolution. What has made French communism so important is precisely its character as a mass-based party in an advanced capitalist country. Therefore it is necessary for historians of the PCF to begin to adopt the techniques of social history in order to explain why so many French workers have voted communist since 1920. It is the aim of this article to make a contribution to such a project by analysing the growth of a communist political consensus in the Parisian suburb of Bobigny during the inter-war years.' In order to understand the social history of French communism, one must consider the Paris suburbs, notorious since the 1920s as the Paris Red Belt. Since the founding of the PCF in 1920, the Paris suburbs have constituted the bedrock of its national electoral base;