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.