Of all the political parties in German history none was more ambivalent than the Social Democratic Party (SDP). Beneath the misleading surplice of Marxism, the SDP was basically only a lower class reformist party. This study shows that, far from continuing revolution, very realistic, ordinary goals of pacification & recovery after WW1 determined the tactics of the SDP. A sober understanding of the importance of foreign policy for the post—war goals of Social Democracy, coupled with the fact that it could not control an electoral majority, led it to abandon its anti—collaborationism of imperial times. By 1930 the SDP was so enmeshed in foreign policy, collaboration, & toleration that it was powerless to summon the workers to battle against Nazism. Illus.