The collection includes correspondence, photographs, manuscripts and printed materials. There are letters from Ekaterina Kuskova (Mrs. S.N. Prokopovich) and photographs of Mark Aldanov, Marie Curie, Aleksandra Kollontaĭ, Ekaterina Kuskova, Pavel Mili︠u︡kov, Mikhail Osorgin, Sergeĭ Prokopovich and Nadezhda Teffi among others. The manuscripts include drafts and typescripts for several dozen articles and chapters as well as untitled manuscripts and notes. The printed materials contain clippings and offprints of articles by Prokopovich, periodicals he edited, and copies of his major books.

Most of the collection consists of manuscripts by Lebedev and others on Russian and East European literary and political topics from about 1914 to the 1930s. There are three microfilm reels of materials on Gavrilo Princip and the asassination of Archduke Ferdinand in Sarajevo, 1914. Correspondents include Hamilton Fish Armstrong and George F. Kennan. There are several drafts of articles by Mark Slonim and materials on the Socialist Revolutionaries in the emigration from about 1930. Lebedev's personal documents cover from his army service (the Russo-Japanese War), through the 1917 Revolution and Civil War, and his later life in Europe and the United States. There are photographs from interwar Albania and Bulgaria, including ones of Aleksandŭr Stamboliski. Printed materials include a copy of Lebedev's book "Novym putem" and issues of "Voli︠a︡ Rossii.".