The Alex mss., 1910-1935, consist primarily of letters from author Upton Sinclair, 1890-1968, to lawyer and fellow socialist, Tanna Alex. The majority of the letters date 1910-1918. They are quite personal in nature as Sinclair discusses his writing projects, relations with and many of the activities of his first wife, Meta, and their divorce. Also present in this portion of the collection are a few letters from Meta to Miss Alex, from Sinclair's secretary, Ellen Barrows, and one from William M. Fuller, as well as four from Fred D. Warren, 1872-1959, and one from Mary Wilshire to Sinclair that the latter apparently forwarded to Alex.

There are no letters from the 1920s but Sinclair again writes briefly in 1934 about his campaign for governor of California and his wife Mary Craig concludes the dated correspondence in 1935 with a note about a "youngster" named Max Knepper and his activities in the EPIC (End Poverty in California) movement. A folder of undated items includes two letters to Sinclair from Helen Grey concerning U.S. Senate hearings and the "fraudulent" sale of Crow Indian reservation lands; a long letter from Sinclair to an unknown, probably female, recipient, and an unsigned note regarding a portrait print that claims it, the print, "is of Tanna Alex herself." The final folder in the collection contains news clippings regarding a fourth of July celebration at the single tax community of Arden and several about the Sinclairs' divorce.