The Allen Sigel Collection of Scores, 1946-1998 contains approximately 27 compositions by Allen Sigel. Many of them are present in multiple versions. There are also ten works by other composers in arrangements by Sigel and three of his didactic works for clarinet.

The Livingston Gearhart Collection of Scores contains compositions and arrangements by Gearhart in published and manuscript forms, as well as sketches and incomplete works. It also contains published scores by other composers annotated by Gearhart.

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.