This article presents an axiological reading of Simone de Beauvoir’s The Second Sex, reframing its most famous sentence ‘one is not born, but becomes, a woman’ as a claim about femininity, love, and alienation under particular conditions of sexual hierarchy. Because this sentence is often taken to express the thesis of The Second Sex on social constructionist readings, Section 1 rejects the aptness of this approach on three grounds. Section 2 outlines an alternative, axiological reading, which better attends to all of the work’s parts, and to Beauvoir’s emphasis on the concrete inseparability of the physiological, sexual, economic, legal, religious, moral, and aesthetic dimensions of women’s situations. Section 3 turns to the sister ‘one is not born’ clause, in Volume I—‘one is not born, but becomes, a genius’—to show that Beauvoir’s account of frustrated freedom in The Second Sex concerns not only alienated labour, sex, and love, but also aesthetic creativity and moral invention. The article arises from a British Academy Lecture delivered on 17 October 2023.