The collection contains 55 manuscript scores, many of them reproductions by photocopy or ozalid, 1 published score, 3 compact discs containing mp3 audio files of 10 works, 2 audio compact discs, and 1 DVD.

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 photocopies of musical scores for 127 tangos for solo piano from 127 composers. The collection also documents the process by which Mikhashoff commissioned and performed the tangos. It includes correspondence, Mikhashoff's research into the history of the tango, and performance materials (i.e. programs and reviews). Composers commissioned for this project include Milton Babbitt, Lukas Foss, Otto Luening, Conlon Nancarrow, Luis de Pablo,and Nils Vigeland.