Archive of approximately 148 letters, memoranda, meeting minutes, party bulletins, financial reports, circulars, and other documents relating to the activities of the Revolutionary Workers League.

The Revolutionary Workers League was formed by Hugo Oehler, Tom Stamm and Sidney Lens in November 1935 following their split from the Workers Party as a consequence of disagreement with the decision by the Cannon-Shachtman faction to merge the Workers Party with the Socialist Party. Based in Chicago, the League remained Trotskyist in orientation until 1937 when Oehler denounced Trotsky for having abandoned Marxism three years earlier. Stamm, however, concluded that Trotsky had gone off track as early as 1928, and he split with Oehler, thus continuing the splintering tendencies of the factious Left Opposition.