The collection contains Lejaren Hiller's personal collections of reel to reel tapes pertaining to his compositional output. It includes recordings of live performances of works as well as recordings of some of the electronic source materials used in other compositions.

The collection of Slee Lecture Recital Recordings contains 94 reel to reel tapes of lectures by the named Slee Visiting Lecturer in the Music Department at the State University of New York at Buffalo.