McMaster came to Ottawa with her family in 1955 and attended First Avenue Public School, Elmdale, Connaught, Lisgar Collegiate (1966), Carleton University (B.A.
in English, 1970; graduate studies in journalism), and Ottawa Teachers' College (elementary certificate, 1971).
While she taught for a few years, McMaster has spent most of her paid working career as an editor, notably at the National Gallery of Canada from 1989 to 2008 as an editor of some 40 art catalogues and founder of the Gallery magazine Vernissage.
McMaster's was the founding editor of the feminist and art magazine Branching Out (1973–1975).
[4][5] She and her husband Ian spend part of each summer at their cottage in Nova Scotia on the Bay of Fundy.