From 1920 to 1939, under the Third Republic, and again from 1943 to 1947, under the Fourth, the French communists were able to present themselves as the harbingers of the future society. But this did not prevent them from improvising, according to circumstances and to the response they received, bold variations on the theme of their relations with the established power and society. The question which so many people are now asking: ‘Have the communists really changed ?’ can be reduced to asking whether, in the fifties although possibly in a confused way, it was not their doctrinal basis which changed; and therefore whether, after a long and victorious battle and with the revolution definitely a thing of the past, we cannot now speak of communist integration, Just as it took sixty years for the modern form of Catholicism to triumph, so perhaps a certain kind of socialist revisionism could now also triumph in similar conditions. To discover whether this is so is the object of the present enquiry.