Henrietta Mabel May was born in 1877. She studied with William Brymner at the Art Association of Montreal from 1909-1912. She also spent a number of years in Paris studying the Impressionists.
In 1916 May returned to Montréal and became an Associate of the Royal Canadian Academy.
In 1918 she painted a number of works depicting women working in ammunition factories for the Canadian War Memorials.
In 1920 May became a founding member of the Beaver Hall Hill Group and in 1933 she was a founding member of the Canadian Group of Painters.
In 1938 she supervised children's art classes at the National Gallery of Canada. She retired in Vancouver in 1950.
She died in 1971.