She attended Bryn Mawr College, where she earned an A.B. degree in 1907. In 1936, she received an honorary degree in Doctor of Letters from Oglethorpe University. She married Cecil Barnes in 1910, and had three sons, Cecil Jr., Edward Larrabee and Benjamin Ayer. In 1920, Barnes was elected alumnae director of Bryn Mawr and served three years. As director, she helped to organize the Bryn Mawr Summer School for Women Workers in Industry, which offered an alternative educational program for women workers within a traditional institution. Consisting mainly of young, single immigrant women with little to no academic background, the summer program offered courses in progressive education, liberal arts and economics. Women in the program were encouraged to develop confidence as speakers, writers and leaders in the workplace.