Fonds consists of manuscript scores, correspondence, published scores and sound recordings of musical compositions and performances by Gregory Levin.

Series consists of draft versions of scores composed by G. Levin.

Fonds consists of four series: Musical Works (1965-2007); Music Business (1970-2012); Other Music Activities (1966-2012); and Education (1969-2000). The predominant series, Musical Works, represents Horwood's activities as a composer, and includes music sketches, full scores, and final scores. The series also includes photographic slides. The Music Business series consists of professional correspondence and other materials pertaining to the production and promotion of Horwood's musical activities. The Other Music Activities series consists of records related to the performance of his music and music arranging. The Education series consists of educational material from Horwood's time as a student and as an instructor.

Series consists of original music scores, parts, arrangements and sketches. Includes pencil scores and copies.