Mary Quayle Innis was an economist, writer, editor, and academic administrator. She was born Mary Emma Quayle in St. Mary's, Ohio on April 13, 1899. From 1915 to 1919 she attended the University of Chicago, graduating with a Ph.B. in English. There she met a young Canadian economics instructor, Harold Adams Innis. After their marriage on May 10, 1921, she joined him in Toronto where he had started teaching in the Political Economy Department at the University of Toronto, and where he remained for the rest of his life.

Quayle accompanied her husband on research tours until their children were born: Donald Quayle (April 21, 1924), Mary Ellen (Sept. 5, 1927), Hugh Roderick (Nov. 17, 1930), and Anne Christine (Jan. 25, 1933). Innis continued writing while at home with her family and published a number of stories in the Canadian Forum. She also wrote An Economic History of Canada (1935; revised and enlarged, 1943) which became a standard university text, followed by two other history texts for use in the schools: Changing Canada (2 volumes, Fish, Fur and Exploration and New France and the Loyalists, 1951-1952) and Living in Canada (1954), written in collaboration with Alex A. Cameron and Arnold Boggs. In the 1940s most of her short stories appeared in Saturday Night (forty-five stories between 1938 and 1947). Several of these were rewritten for inclusion in Stand on a Rainbow, (1943), an autobiographical "novel". For ten years Innis was editor of the YWCA Quarterly, and in 1949 she wrote a history of that organization, Unfold the Years, a survey of the growth of the Young Women's Christian Association in Canada from its inception in 1873.

After her husband's death in 1952 Mary Quayle Innis entered a more public life. In 1955 she became Dean of Women at University College, where she served for nine years. She was a Canadian delegate to the Commonwealth Conference on Education held in Oxford in 1959. After her retirement she became vice-chairman of the Committee on Religious Education in the Public Schools of the Province of Ontario. Innis received an LL.D. from Queen's University in 1958 and one from the University of Waterloo in 1965, in recognition of her literary and academic achievements

During these years, Innis continued to write and publish stories and also worked as an editor. Travellers West appeared in 1956 as well as a selection of her husband's articles and addresses, Essays in Canadian Economic History, followed by Mrs. Simcoe's Diary in 1965. Innis also worked with two university groups to edit commemorative anthologies, The Clear Spirit (1966), the centennial project of the Canadian Federation of University Women, and Nursing Education in a Changing Society (1970), for the fiftieth anniversary of the founding of the School of Nursing at the University of Toronto.

Mary Quayle Innis died suddenly on 10 January 1972, the day before her revised edition of Harold Innis's Empire and Communications appeared.