Born at Cambridgeport, Mass., was educated by her father, read Ovid at the precocious age of 8, and as a young woman developed friendship with the Trascendalists, who accepted her as their intellectual equal. From 1839 to 1844 she held a series of conversational classes at Elizabeth Peabody's home, and had a strong influence on the most cultivated circle of Boston society.

In her discussio with this group originated the material of her book Woman in the Nineteen Cewntury (1845), the first mature consideration of feminism by an American, touching every aspect of the subject, intellectual, economic, political, and sexual.

In the summer of 1846 she visited Europe. In Italy she was an ardent adherent of Mazzini, and married one of his followers, the Marquis Angelo Ossoli. The ship that brought them in the U.S. was wrecked in a storm off Fire Island, near New York. The body of her child was the only one recovered, and her manuscript on the Roman uprise of 1848-49 was lost.