Simone de Beauvoir’s work has been a great inspiration for feminist philosophers. This chapter explores her legacy to the discipline. I begin by examining the opening question of The Second Sex: What is a woman? I argue that one of Beauvoir’s distinctive contributions was to put this question on the philosophical map. While her account of woman has been criticized-for example, for privileging the experiences of white middle-class women-her phenomenological approach to sexual difference can be appropriated to expand the scope of her analysis. I also discuss her iconic line, “One is not born, but rather becomes, a woman” and claim that it should not be read in terms of the traditional sex/gender distinction. Such an interpretation misconstrues her conception of the body, which for her is never merely a natural object, but rather a situation wherein nature and cultural interpretations are intertwined. In addition, I consider the issues, such as economic power, legal status, and reproductive rights, that Beauvoir considered central to women’s liberation.