ENAn attempt is made in this study to bring together material on one of the most interesting, important, and controversial episodes of recent history-the period of the Soviet-German Non-Aggression Pact of 1939. An examination of recently published materials and the large collections of documents gathered by the prosecution and defense for the Nuremberg trials has produced such an amount of evidence concerning German-Soviet relations in the period from 1939 to 1941 as to warrant a presentation of the course of events in that period in the form of a chronological survey. It should be noted that in the account of the events leading up to the signing of the Pact, generally available evidence and episodes previously analyzed by several competent historians have not been treated at such length as has the later period for which much of the relevant documentation has hitherto remained unknown. The free and complete access accorded the writer by the Law School of the University of Chicago to its vast collection of documents, transcripts, and other materials from Nuremberg has made this work possible. The large number of unpublished documents cited through out the text indicates that the search through these mountains of paper, though tedious, is rewarding. The Divisions of Manuscripts and Aeronautics of the Library of Congress have kindly permitted access to some interesting German documents in their custody. [Extract, p. v].