The triumph of the modern feminist movement in Western society over the past thirty-odd years is unprecedented in human history. Although feminism has had many important effects on a range of social practices, the story of its march is, at its core, the story of large numbers of women for the first time being permitted to engage in activities and occupy social roles formerly reserved to men. This change postdates, but itself completely coincides with[,] a development associated with modernity – the creation of modern labor markets. In the wake of feminism, those markets have seen the steady demise of practices that prevented women from offering, or employers from accepting, women's and men's labor on the same terms.

Without giving a full account of how and why these changes occurred, it is sufficient to say that traditional sex role norms have suffered grievously in recent years. Although powerful conventions and expectations still underwrite pronounced occupational segregation in partial disregard of talent or preference, the range of jobs open to women has dramatically expanded. Men and women are now closer to occupying a unitary labor market than ever before, with the consequence that competition for women's labor is keener than in the past. Women's pay is rising and approaching parity with that of similarly qualified men. As a result, the opportunity costs of alternative allocations of time and effort in the unpaid domestic sphere have never been greater. For well-educated women, the payoffs forgone by choosing to work at home are large.