In 1963 the Social Democratic Party of Germany(SPD)celebrated its hundredth anniversary. When we look back historically minded on this rather eventful development of a party within one hundred years it is rather interesting to find out a point in the long course of its history at whiCh the party was almost crashed by external pressure-namely from the Nazis(NS) and from the divergent resisting powers of the left wing. This consideration gives rise to two questions which in fact were of fatal importance to the further development of this party during the War and after it as well. First of all, how it was possible that a great party such as the SPD which after World War I had initiated the Weimar Republic could almost completely be smashed by NS-policy. After World War II the party in its Godesberg Programme decidedly proclaimed the tendency towards its further conservative development. In respect to this the other question is how the members of this party in spite of the violent discussions and conflicts with its opponents (communists, left-wingers from the own party, "New Beginners", etc.) stuck convincingly to the moderate revisionist policy of the party in those both financially and politically difficult times from 1933 to 1945. By stating these problems as mentioned above the author in the second paragraph of his study first tries to give an outline of the process of the SPD's dissolution and of the rise of National Socialism. In the third pragraph, however, he also gives a detailed account nf the movement of resistence during the Prague emigration of the party. Finally he convincingly observes that the SPD of today, that is to say, the present party in power in the Federal Republic-seen in the context of the history of ideas-is basically still persuing its party politics of the thirties aiming at realizing liberty and the parliamentary system.