May Wright Sewall (1844 – 1920) was an American feminist, educator, and lecturer. She was born in Milwaukee, Wisconsin in the United States. In 1866, she earned a bachelor's degree, and in 1868 she earned a master's degree, both from North Western Female College. In 1872, Sewall married Edwin W. Thompson and lived in Indianapolis with him. Three years later, Thompson died.
Sewall became interested in woman suffrage. She attended a national convention in 1878. In 1880, she married Theodore Lovett Sewall, who was head of a Boys' Classical School. With her husband, she founded and headed the Girls' Classical School. For years it was one of the three leading girls' schools in Indianapolis, Indiana.
Sewall was also a charter member of the Art Association of Indianapolis, the Propylaeum, and the Contemporary Club. Throughout her life she helped in campaigns for female suffrage in various Midwest states. Beginning in the 1890s, Sewall carried her feminist interests further abroad. She was elected president of the National Congress of Women in 1891 and of the International Congress of Women in 1899. She combined these activities with working for peace. In 1904, Sewall became chairman of the ICW standing committee on peace and arbitration. In 1915, Sewall chaired an Organized Conference of Women Workers to Promote Peace, and in 1915, she was a member of Henry Ford's Peace Expedition.
In 1907, Sewall sold the Girls' Classical School to Anna Weaver. Disappointed at the amount she had received from Weaver, Sewall had to depend on income from lecturing about women's rights, on peace and arbitration, and on psychic research. Psychic research had been one of her interests since the 1880s, and she moved to Eliot, Maine, where there was a center on the subject. In 1920, Sewall wrote a book on her psychic experiences, Neither Dead Nor Sleeping. She also wrote three more books The Higher Education of Women, The Woman Suffrage Movement in Indiana, and Women, World War and Permanent Peace (1915).
The nineteenth amendment was ratified a month after Sewell's death.