John Cage was an American composer and music theorist, and a leading figure of the post-war avant-garde. The Cage Correspondence collection is comprised of correspondence and ephemera including letters, cards, clippings, catalogs, photographs, negatives, cassette tapes, music scores, and art.

This is correspondence that is related to John Cage but was not given to Northwestern by the composer. Letters are between Cage and the person in the folder's title unless otherwise indicated in the container list. Of particular interest are letters from John and Xenia Cage to friends in California that relate their experiences while living in Chicago in the early 1940s.

Kaikhosru Shaburji Sorabji (1892-1988) was an English-Parsi composer and music critic active for the majority of the 20th century. This collection of letters between Kaikhosru Sorabji and Baron Arnold Hartzhorn are primarily from February 1950 to August 1966 and discuss opinions on music, music criticism, religion, and briefly touching on the personal life of Sorabji. This collection is one archival box.