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).

Maurice Peress (1930-2017) was an American orchestra conductor, arranger, author, and educator. The papers include audio and video recordings, clippings, contracts, correspondence, diaries, memorabilia, notebooks, photographs, posters, programs, research materials, reviews, scores, scrapbooks, and working files, sketches, and other materials.