Born in Wisconsin, May Wright Sewall earned bachelor's and master's degrees from North Western Female College in Illinois. In the early 1870s, she moved with her first husband to Franklin, Ind., where she became a high school principal. He died three years after they married. In 1880, she married second husband Thomas L. Sewall, founder of the Indianapolis Classical School for Boys. In 1882, the couple opened the prestigious Classical School for Girls, which prepared young women to attend eastern colleges.
May Sewall helped found the Equal Suffrage Society of Indianapolis. She was a leader in the National Woman's Suffrage Association and the National Council of Women of the United States.
Sewall contributed to the civic and social life of Indianapolis. She was co-founder of the Indianapolis Woman's Club and charter member of the Art Association. She conceived the idea for the Indianapolis Propylaeum, a club owned and managed by women.
She became interested in the peace movement in the 1890s. For many years, she wrote and gave speeches on international understanding and cooperation.