The Katherine Gee Hornbeak Papers contain items related to Professor Hornbeak's affiliation with Smith College and her own education. There is extensive correspondence from her sisters Harriett Lee Hornbeak ("Hattie") and Louise Hornbeak. In addition there is correspondence with Ruth Hillyer Hill, Katherine Strayer and Anne Francis (Smith College, M.A., 1942; Headmistress of the Pontypool Girls' County School, Penygarn, Wales, 1945-1960s) and from various students and friends.

Professor Hornbeak's research and lecture notes reflect a teacher's use and reuse of notes throughout her teaching career. A file may contain notes for a particular course in a given year, but it is more apt to contain notes from a succession of years (sometimes dated to show succession). Folders labels suggest a date for a course as noted by Hornbeak but materials included may reflect a range of dates. Also there are situations where a particular file will include papers related to more than one course number. Duplication between files does occur and notes on a particular topic may appear in more than one file. For the most part files are as Professor Hornbeak left them and reflect these many apparent date and course conflicts.

• Series I: General materials (1930s-1985)
• Series II: Correspondence (1916-1985)
• Series III: Publications
• Series IV: Lecture and research notes
• Series V: Oversize materials