Why do peasants from Limousin often vote communist and the Alsacian workers tend to vote more to the right? Why do the French differ so profoundly in their attitudes towards immigration, religion, marriage, AIDS, death and birth? In order to answer these questions, the author employs all the recent tools of political sociology, from demographic analysis to history. With depth and astuteness, he reveals that behind the mask of a united and indivisible nation lies the hidden face of a pluralistic and little-known France.Herve Le Bras is the Director of Studies at the School of Advanced Study for Social Sciences and the Research Director at the National Institute of Demographic Study.