The papers include correspondence, subject files, photographs, and printed materials. The majority of the collection concerns the mission of the American Red Cross to Russia in 1917-1918; Thacher served as a secretary of the mission. There are letters and telegrams by W.B. Thompson and Raymond Robins, records of supplies, shipments, and distribution reports and over 600 photographs from Russia, China, and Romania. There is substantial correspondence from 1918-1919 concerning Russia, including letters by Louis Brandeis, Felix Frankfurter, and Lillian Wald. A substantial part of the collection concerns Russian war relief in 1941-1942, an area in which Thacher was active. Printed materials include a pamphlet and an article on Russia prepared by Thacher after his return from that country in early 1918.