Under the conditions of political isolation of Bolshevik Russia by Western countries, the 100th anniversary of Leo Tolstoy (1928) was celebrated in the USSR with great pomp. The solemn celebration went beyond a cultural event and acquired an ideological and propagandistic character. It was an important part of the cultural diplomacy of the young Soviet state, a matter of its prestige, since many foreign guests were expected. The only representative of the United States at Tolstoy’s centenary was Henry Wadsworth Longfellow Dana (1881–1950), an American scholar and university professor, whose name is practically unknown in the field of Tolstoy studies and in the Russian academia in general. The paper gives a detailed day-by-day reconstruction of H.W.L. Dana’s participation in the centenary based on the materials of the Soviet press and Dana’s Russian diary stored in one of his archives in the US. As a pro-Soviet intellectual and a friend of new Russia, Dana played a significant role in enhancing public interest to the creative heritage of Tolstoy in the States. The paper introduces in scholarly discourse unpublished materials from the Department of Manuscripts of the State Museum of Leo Tolstoy (Moscow), A.M. Gorky Archive at the A.M. Gorky Institute of World Literature of the Russian Academy of Sciences (Moscow) as well as unknown American sources, including The Longfellow House – Washington’s Headquarters National Historic Site (Cambridge) and The Houghton Library at Harvard University (Cambridge).