Papers, letters, memoranda, memorabilia, and manuscript music scores assembled by and related to the life and musical activities of Anton Seidl. The collection includes many letters from Cosima Wagner and her children addressed to Anton Seidl and his wife, the opera singer Auguste Kraus Seidl. There are also letters from Lilli Lehman, Edvard Grieg, Antonin Dvorak, Bronislaw Hubermann, Carl Goldmark, Maud Powell, Marianne Brandt, Felix Weingartner, Lyman Abbott, and many others. The letters are chiefly concerned with musical performances, composition, and related affairs. There are journals, diaries, and memoranda in Seidl's hand, as well as photographs and clippings relating to his conducting career. Also, twenty-seven manuscript scores of Seidl's orchestrations of various works.

Manuscript materials which include correspondence, business papers, composition scrapbooks and musical scores; books; clippings; records; and photographs.

Manuscripts of musical scores, memorabilia and photograph. Folder 1 of the collection includes a general index (d. March 1945), photograph, awards, 5 citations, and a biographical sketch. His musical compositions (folders 2-26) are divided in three major categories: sacred and non-sacred vocal music, and musical compositions for instruments. His sacred choruses for mixed voices has been highly praised. His non-sacred vocal music seems to deal with children, nature, and poetic topics; also included are arrangements of Stephen Foster's songs for choruses. Among his musical compositions for instruments are some with Caribbean or West Indian themes