Series consists of publications (mainly "underground" newspapers), manuscripts, notes, and audio recordings of Maillard's radio show The Underground News on WBUR Boston University Radio. Material is arranged in four sub-series: Underground Writings, Reference, Correspondence, and Audio Recordings.

Series consists of correspondence, manuscripts, and notes regarding a proposed book by Maillard: a series of critical biographies of British Columbia authors who write in the style of "magic realism."

Series consists of correspondence between Maillard and other writers, arranged by individual or organization, fan mail, and personal mail.

Series consists of records from the research conducted by Keith into his family history. It consists of correspondence, research, photographs, audio recordings, and interview transcripts. This series includes information that was used in Keith’s memoir Fatherless. Material arranged in two sub-series: Files and Audio Recordings.

The series consists of ephemera of Keith’s father, Eugene C. Maillard. It includes correspondence, audio recordings, scrapbooks, photographs, society memberships, financial records, the final will, and other personal information. Information from this series was used to create Keith’s memoir Fatherless. Material arranged in two sub-series: Files, Photographs and Audio Recordings.

The fonds consists of manuscripts of his novels and short stories, issues of underground newspapers, audio recordings of Maillard's radio shows, musical scores, correspondence with other writers, and reference files for his works. It also contains extensive electronic backups of his manuscripts, digital notes, and journals on floppy diskettes. It also contains artwork and photographs of important objects, people, and places.

The series is divided into two subseries, Textual Materials and Electronic Backups. Textual materials consist of manuscripts of novels and short stories. The arrangement, primarily chronological by published work, also reflects two peculiarities of his writing style. First, he labelled some as the final draft prematurely rather than numbering successive drafts. Some of his novels, therefore, have several "final" drafts. As best as possible, these have been arranged in chronological order. Also, during the creative process and modification of draft versions, Maillard created what he calls "spin-off," including ideas that are developed on the side but never added into storyboards developing the arrangement of the scenes and pages removed from a draft version. Other segments of the spin-off are unidentifiable beyond the novel to which they belong; these have been given a letter designation (A, B, C) to indicate which files were found together. The letter does not imply any sense of order, chronological or otherwise. Spin-offs with uncertain chronology have been filed at the end of each manuscript sub-series with specific research notes and related miscellaneous files. Some files contain UBC-related correspondence. The electronic backup consists of copies of the textual materials.

Series consists of correspondence, manuscripts, notes, and materials related to the book and general publicity. It also contains general personal files. Material arranged in two sub-series: Files, Audio Recordings, and Video Recordings

The series consists of musical scores of Maillard's arrangements for the Ferron Band, notes, and clippings. Material is arranged in two sub-series: Scores and Miscellaneous.

Series consists of records related to the publication of articles and podcasts on various websites, mostly his website: https://keithmaillard.com/, that feature his views on culture and short stories and his writing interests. The series is divided into two subseries – Textual Records and Audio Recordings.

Series consists of photographs of Keith, his family, friends of his father, and interesting locations. It also consists of artistic photographs taken by Keith and a painting of Gene Maillard. The series is split into Photographs and Portraits.

Series consists of newspaper, book chapters, magazine clippings, and notes on subjects related to Maillard's writing projects or of general interest to him.