English feminist philosopher, essayist, and political theorist. Writing in the 1850s, she was one of the first essayists in England to press for women's rights and suffrage, claiming full legal and political citizenship and equality in higher education. Among her works are the important Essays on Sex Equality.
She collaborated with the philosopher John Stuart Mill, her second husband, on his classic expression of feminist thought, The Subjection of Women (1869).
Mill was born in London, but little else is known of her early life. Her essays authoratively rejected the legal and political traditions subordinating women, and claimed that the remedies for the improvement of women's position lay in education, law and politics. She advocated women's suffrage as early as 1851. Unable to remain politically active due to bad health, she continued to pursue her cause through the activities of John Stuart Mill.