This collection consists of personal correspondence, notes, reports, and financial records. The majority of these relate to Mortimer Waldo's activities in Russia and Finland from 1916 to 1918.

Letters to family and friends written from 1916 to 1917 describe life in Siberia and comment on the political situation in the United States and the entry of the U.S. into the First World War. Later letters (1918) concentrate on the Finnish Civil War. Those dating from after 1919 primarily relate to Waldo's business travels for the Novo Engine Company and REO Motors, but also include personal letters from friends in Russia, Finland, Germany, and Japan.

Waldo's personal notebooks include observations on the Russian Revolution, international affairs, and war, informal reviews of books he read, notes made during his travels through Finland in 1918, and lists of personal expenses.

The official records relating to his YMCA service and his term as Vice-Counsel are few, but there are several reports prepared by Waldo. The most important of these recommended that the Allies recognize an independent Finland, and was used by the historian Samuel E. Morison in his report to the U.S. Department of State on the Peace Settlement.