By 1924, Gillis's two sons, Chase H. and Kenneth J., assisted their father at the A. O. Gillis Funeral Home. The firm moved to a new site at 400 N. 7th Street the following year and in the mid-1930s became known as A. O. Gillis & Sons. In 1940, the funeral home moved again to a more spacious location at 802 Chestnut, was called the Gillis Memory Chapel, and advertised lady attendants and an ambulance service.

When A. O. Gillis died on April 4, 1941, his son Kenneth became funeral director. By 1954, Kenneth's own son, Michael C. Gillis, joined the family business as assistant director and eventually became president of the firm when his father retired in 1966. The Gillis Memory Chapel moved to a new building at 4201 S. 7th Street in January 1974. In 1981, the Gillis Memory Chapel was acquired by Callahan Funeral Home, Inc. and the name changed to the Callahan-Gillis Funeral Home, South Chapel, for a short transitional period between ownership. By 1982, the name Gillis was dropped and 4201 S. 7th Street property was owned by Callahan Funeral Home (South Chapel).

This collection contains nearly a complete set of funeral registers from the A. O. Gillis Funeral Home from its inception in 1916, when Gillis left the H. L. Stees firm, to the time when the Callahan Funeral Home, Inc. acquired the Gillis property in 1981.

The collection is arranged in two segments. The first half includes twenty funeral register books in which funeral records were generally recorded in chronological order (1916-1938). At the front of each ledger book there is an alphabetical name index of the deceased registered. Information recorded includes all or part of the following: name of deceased, residence, age at death, date of death, cause of death, date of burial, place of burial and description of funeral arrangements and cost. Beginning around 1928, obituaries were clipped from the local newspaper and attached to the individual's funeral record.

Many loose, miscellaneous items were found in between pages of most of the ledger books. These items were removed and placed in corresponding acid-free folders. They include either general correspondence and financial statements regarding the operations of the funeral home or direct references and records pertaining to individual funerals.

The second half of the collection contains funeral registers on 5" x 8" index cards. They are arranged in alphabetical order by name of the deceased and cover the years 1938-1981. The cards contain information on funeral arrangements and cost and a copy of the death certificate (which includes name and address of deceased; date, place, and cause of death; spouse; date and place of birth; names of father and mother and their birthplaces; list of survivors). Sometimes other items regarding the death, funeral or burial will be clipped to the card or an obituary will be glued to it.