The letter which follows has never before been published and was only recently located in the Amsterdam Institut fur Sozialgeschichte. It is a document of exceptional historical importance, both for its author and its addressee, and the circumstances in which it was written. The authoris Dr. Julius Deutsch, a prominent Austrian Social Democratic leader in the First Austrian Republic. Deutsch served as a member of parliament and was head of the Social Democratic paramilitary Schutzbund. He and Dr. Otto Bauer were to play key roles in the workers' uprising in Vienna and other parts of Austria in February, 1934—four months after the letter was written. The letter was addressed to the eminent Karl Kautsky, a leading Social Democratic theoretician during the interwar period, and its message casts new light on the thinking of both Deutsch and the leadership of the Austrian Social Democratic Party shortly before the fateful revolt.