ABSTRACT This paper explores the background to Mill’s feminist thought by relating his Subjection of Women (1869) to his early piece ‘On Marriage’ (1832) and three contemporary essays that were written among the radical Unitarian community of South Place Chapel by Harriet Taylor Mill, William Bridges Adams (1797–1872), and William Johnson Fox (1786–1864). It seeks to demonstrate that Mill’s Subjection of Women (1869) still has close ties with the earlier feminist thought of the South Place Chapel circle. Specifically, it will show that key arguments like the characterisation of marriage as slavery, the pernicious moral effects of gendered education, and the social benefits of women’s liberation feature in the early essays by Mill himself, Harriet Taylor Mill, William Bridges Adams, and William Johnson Fox as well as in Mill’s Subjection.