Professor of German at the University of Michigan and Columbia; mostly correspondence of Thomas with his family, professional colleagues, publisher, etc.; also some correspondence of his wife after his death; speeches, lecture notes, biographical sketches; papers include material on language studies at Michigan and Columbia, attitudes of academia toward Germans in World War I, accounts of European travels in 1877, 1896, and 1900; Civil War letter of Steven Thomas, Calvin's father.
The collection has been arranged into the following series: Biographical/personal material; Correspondence; Lectures and addresses; Journals/diary; Scrapbooks; Other family members papers; and Publications.