She was the youngest speaker at the 1852 National Women's Rights Convention held in Syracuse, New York. She was a tireless worker and public speaker, and contributed numerous articles to the press, being regarded as "one of the most logical, fearless and scientific writers of her day". During 1878–1881, she published and edited the ''National Citizen'', a paper devoted to the cause of women. With Elizabeth Cady Stanton and Susan B. Anthony, she was for years in the forefront of the suffrage movement, and collaborated with them in writing the ''History of Woman Suffrage'' (1881–1887). She was the author of the ''Woman's Rights Catechism'' (1868); ''Woman as Inventor'' (1870); ''Who Planned the Tennessee Campaign'' (1880); and ''Woman, Church and State'' (1893).
For many years she was associated with the National Women's Suffrage Association, but when her views on suffrage and feminism became too radical for many of its members, she founded the Woman's National Liberal Union, whose objects were: To assert woman's natural right to self-government; to show the cause of delay in the recognition of her demand; to preserve the principles of civil and religious liberty; to arouse public opinion to the danger of a union of church and state through an amendment to the constitution, and to denounce the doctrine of woman's inferiority. She served as president of this union from its inception in 1890 until her death in Chicago, in 1898.