This article is based on documents in the archives of the Soviet Commissariat of Foreign Affairs, many of which have not been previously published. This extra material allows one to see the development of Soviet policy at closer hand though there is still much that remains obscure. The correspondence between Litvinov, the Commissar for Foreign Affairs, and Stalin, despite the absence of the latter's answers, is particularly valuable as it further illuminates their working relationship and reveals some of the differences between them. The exchanges between Litvinov in Moscow and the Soviet polpred, Alexandrovsky, in Prague show clearly that the latter was repeatedly cautioned against encouraging the Czech leaders to think that they could rely on the unilateral assistance of the USSR. They reveal, too, the degree to which Litvinov and Potemkin, a deputy commissar, felt that Fierlinger, the Czech minister in Moscow, was misrepresenting the Soviet position in this respect. Additional evidence cited here confirms earlier views that the Soviet leadership was not prepared to act independently of France or outside the League of Nations even when the opportunities for assisting Czechoslovakia were available. The article ends on a cautionary note, pointing out the limitations of the foreign ministry archives as a guide to the inner dynamics of Soviet diplomacy.