 To begin an overview of feminist metaphysics in this century, it is helpful to return to Simone de Beauvoir’s classic work The Second Sex (Beauvoir 1949). Two of her most famous claims appear to have profound metaphysical implications: “One is not born, but rather becomes, a woman”, (Beauvoir [1949] 1989: 267) and “He is the Subject, he is the Absolute—she is the Other” (Beauvoir [1949] 1989: xxviii). There is disagreement about how to interpret both claims, yet to many the former serves as the slogan for the view that gender is socially constructed, and the latter identifies the content of feminine construction as what is opposed to the masculine, the masculine also being what counts as the subject or self. Three interconnected themes prominent in feminist metaphysics emerge here: (i) the social construction of gender (and other categories), (ii) the relational nature of the self (and other categories), (iii) the dangers of dualistic thinking. We will conclude by mentioning the challenges feminist metaphysics poses to the content and practice of mainstream metaphysics.