Gould's papers fall into two series. Family correspondence covers the years 1856 to 1860, when Joseph and his brother Charles were travelling in Europe, and consists of letters home from both young men, and their parents' replies. Manuscript music comprises two volumes of church anthems, with some organ music; some are original compositions by Gould and Samuel Warren. Related to this is Gould's brief manuscript account of the origin of the Mendelssohn Choir. Some family photographs are also included.

The Montreal Mendelssohn Choir Collection comprises several volumes of sheet music from the Choir’s library. The choral folios were compiled and bound into eight volumes at the time of their donation to McGill University in 1895. The estate of D. Torrance Fraser, a former Choir member, donated another four volumes of choral music in 1926 and 1927. Three volumes contain second copies of the pieces from the Choir’s library donated thirty years prior; the fourth volume donated in 1927 contains a number of pieces performed by the Choir but not found in the seven extant volumes from the Choir’s library.