Armed with charts and masses of data, Bartolini has produced a colossal study of the relations among European labor parties and unions, governments, and bourgeois interests; the role of peasants and religious groups; and the complex split between socialists and communists. He argues that the rigid class identity (or "cleavage") of workers became ideologically hostile to the state, with socialism as a final step in the "mass nationalization and integration of the lower classes in the national political order." In this process, the scope of political representation and citizenship proved far more important than economic development and industrialization. He concludes by arguing that the class cleavage is now in decline, largely because of changes in the social structure. Bartolini's erudition, mastery of details, awareness of national differences, and virtuosity in explaining problematic cases are astounding. But it is arguable whether even such a clearly written social-science study could throw more light on this subject than less "scientific" but more historically grounded studies. Indeed, the latter might better convey the distinctive flavors of the movements and nations considered -- and be more readable.