 Margaret Fuller (1810–1850), one of the most important American feminists of her day, was a philosopher, journalist, and literary critic. She belonged to the New England intellectual community called the transcendentalists, who also included Ralph Waldo Emerson and Henry David Thoreau. Her most important written work is Woman in the Nineteenth Century (1845), an expansion of her article entitled “The Great Lawsuit: Man versus Men, Woman versus Women” (1843). Fuller is remembered not only for her writings, but also for her life: a series of undertakings to live up to her own ideal of transcending the then customary gender differentiations. This article will present a summary of her philosophy and also take note of the various ways in which she sought (or did not seek) to implement her philosophical ideals.