Papers documenting Helen Sawyer Hogg's career as an astronomer and her personal life. Included is personal and professional correspondence, diaries, course and lecture notes, addresses, interviews, manuscripts, research files (especially on star clusters), catalogue awards, photoprints, slides, sound recordings, and videos. Also portions of the personal records of three other astronomers: her first husband, Frank Scott Hogg (1922-1952), documenting, in particular, his years as an astronomy student at the University of Toronto and Harvard University; of Ruth Josephine Northcott (1932-1969), and Clarence Augustus Chant (1930s-1940s), the founder of astronomical studies in Canada.