In this paper, new social movements in France and West Germany are compared in terms of their supporters, and in terms of certain elements of the political and administrative conditions which they are confronting. On the basis of survey data from 1982, specific attributes of supporters of new social movements (socio-demographic characteristics, value orientations, and attitudes) are highlighted which distinguish them from the average of the population. While broad similarities exist between supporters in both countries, the new social movements in France appear to be less distinct from mainstream society than their West German counterparts. The examination of the political and administrative conditions focuses on the centralization/decentralization of the State, and the party and electoral system in France and the Federal Republic. A decentralized system is argued to offer, on the whole, more favorable conditions for the protest movements. Also the West German party system, and the West German electoral mechanisms have helped the new social movements east of the Rhine. / M.A.