Born in 1876 in Springfield, Illinois, Ethel Mars was an only child whose father worked for the Wabash Railroad. In 1892, at the age of seventeen, she enrolled in the Cincinnati Art Academy where she remained for two years. She dropped out briefly, probably for financial reasons, but resumed her studies at the Academy in 1894. Mars was a student of Frank Duveneck and L.H. Meakin, both of whom championed her work.
While at the Academy, Mars met fellow student, Maud Hunt Squires, who became a life-long companion. After graduation, Mars and Squires moved to New York City and found work as book illustrators. They traveled to Europe in 1902 where they studied the old masters and visited exhibitions of contemporary art in Paris and elsewhere.
A joint exhibition of Mars’ and Squire’s illustrations was held in 1903 at the Cincinnati Art Museum and in the year that followed, the museum mounted another exhibition of their paintings, drawings and prints. Around 1906, Mars and Squires relocated to Paris and, with the exception of a period spent in Provincetown during WWI, they remained in France for the remainder of their lives.
Mars exhibited frequently in the United States and abroad and from 1907 to 1913, her work was seen in the Paris Salon. She also had exhibitions at the Pennsylvania Academy of Fine Arts, the Society of Western Artists, the Art Institute of Chicago, the Corcoran Gallery, Provincetown Art Association and elsewhere.