The Theodore Spicer-Simson Collection contains the Spicer-Simson medallions as well as photographs, correspondence, typescripts and other related material.

The bulk of the collection consists of the Spicer-Simson medallions. These are portrait medallions cast in bronze of major world and literary figures from Spicer-Simson's lifetime. All of these were sculpted from life. Notable among these are David Fairchild, Padraic Colum, Henry Ford, Sir Ernest Rutherford, Sherwood Anderson, Theodore Dreiser, Franklin Delano Roosevelt, and other important figures in addition to person friends and family members of Spicer-Simson.

The collection contains many other examples of Spicer-Simson medals in the form of medals, awards, and sculptings that Spicer-Simson created. Included in these are medals sculpted for the National Academy of Sciences, Princeton University, the Guggenheim Foundation, and the U.S. Congress. The collection also contains clay and plaster molds of medallions, including some small pieces of sculpture. In addition to all his sculpture and medallions, the collection contains examples of Spicer-Simson's other artwork in the form of sketches, drawings, and bookplates.

Spicer-Simson's autobiography, A Collector of Characters is held in the collection, along with the typescripts of the book. The collection's correspondence includes correspondence from Hervey Allen, Padraic Colum, H.L. Mencken, Eleanor Roosevelt, Sir Ernest Rutherford, and Marjory Stoneman Douglas. The photographs include mostly photographs of medallions and sculpture, including some not in the collection, but also contain many photos of Spicer-Simson's subjects, some of these mounted and autographed.