The history of malacological exploration of Siberia, made in 1932 and 1933 by the malacologist Alan Mozley, then affiliated with the Smithsonian Institution, USA, is given, with a discussion of his contribution to the knowledge of taxonomy, biogeography and ecology of freshwater and terrestrial molluscs of Northern Asia. The type specimens of the Siberian species and subspecies, described as new by Mozley, are illustrated, with remarks on the current taxonomic status of these taxa. A social-historical context of Mozley’s trip to Stalin’s Russia is also provided, including its connection to the prosecution of Nikolay Vavilov, a key opponent of “Lysenkoism”.