The collection contains 13 boxes of concert programs, chiefly from England, but also including Buffalo, New York, and other cities in the United states, Austria, German, and other European countries, as well as Mexico and Canada.

The collection contains approximately 1300 scores, half of which bear markings entered by Mikhashoff or his colleagues in preparation for performance. The collection includes manuscripts and print publications, both originals and reproductions.

The collection contains 249 cassettes featuring performances either by Mikhashoff or of his music, 801 non-commercial cassettes and 115 commercially-released cassettes that do not contain performances or works by Mikhashoff.

The collection contains 155 reel to reel tapes featuring performances either by Mikhashoff or of his music, 31 reels that do not contain performances or works by Mikhashoff, and 19 reels containing tape parts to accompany performances. Five LP sound recordings and nine compact discs are also included in the collection.

The collection contains thirty-one video and eight audio recordings on video cassettes, most with Yvar Mikhashoff present as performer. One video title is missing, represented only by photocopied leaves of the container.

The collection contains 423 indexed images and approximately 350 additional, un-indexed snapshots. The images include publicity shots, professional photographs and snapshots of Mikhashoff in rehearsal and performance, and snapshots from some of Mikhashoff's travels. Other people included in the images include noteworthy performers and composers, such as Aaron Copland, Virgil Thomson, Sylvano Bussotti, Henri Dutilleux, Giacinto Scelsi, Toru Takemitsu, Frederic Rzewski, Luis de Pablo, Henry Brant, John Cage, Milton Babbitt, Conlon Nancarrow, Nils Vigeland, and Poul Ruders.