Women's unpaid work at home has not concerned theorists of social justice, despite the fact that it renders women vulnerable to exploitation and, therefore, injustice. Through a discussion of various conceptions of work and women's work in the materialist tradition of thought, the author develops a theory of women's work as care. By focusing on the material, psychological and gendered aspects of care, the theory elucidates how and why care is exploitative as long as it remains women's work, and what problems it poses for conceptions of social justice.