Letters, notes, programs, photographs, and printed materials. The collection is comprised primarily of handwritten correspondence between Reiner and notable music figures including Samuel Barber, Leonard Bernstein, Aaron Copland, Lukas Foss, Darius Milhaud, Arthur Nikisch. Arnold Schoenberg, Richard Strauss, Igor Stravinsky, and Leo Weiner. Also of note, letters from writer and conductor Gian Francesco Milpiero and his wife Auna detailing wartime conditions in Italy (1946).

Correspondence, manuscripts, papers, essays, etc. relating to Berlioz, and 19th century arts and literature. The correspondence includes original Berlioz letters and over 200 copies of letters relating to Berlioz and the romantic era, written by musicians, critics, historians, and literateurs of the past century. There are many photostats of letters and manuscripts obtained from the principal libraries of the world which hold original Berlioz material. The collection includes much printed material in the form of music scores, published letters, essays, clippings, biographies, music and book catalogues, program notes, and playbills.