This Article interrogates the sexual morality of Equal Protection. Gender equality jurisprudence reveals the unacknowledged influence of a traditional, heteronormative conception of sexual morality—the sexual double standard—that often sets the parameters of gender equality. When the U.S. Supreme Court frames a gendered law as limiting participation in education, the workplace, or civic life, it tends to apply a demanding form of heightened scrutiny that few gendered laws can survive. When, on the other hand, it frames a gendered law as governing the consequences of illicit sex, it tends to apply what I call the sex discount, replacing the rigorous scrutiny mandated by its public equality cases with an unacknowledged, much more deferential form of equal protection review. The Court invokes biological differences between men and women to justify this deference. But the sex discount does not genuinely accommodate gender differences regarding pregnancy, sexuality, or parenthood. Courts tend to reject reproductive justifications for inequality in public life; they tend to assume that biological differences are irrelevant when a heterosexual couple is married; they have applied the sex discount to gendered laws that serve no interest in protecting fetal life; and they apply a sex discount in cases of antigay discrimination that do not involve reproductive or sexual behavior. Rather, the sex discount authorizes governments to use gendered laws to enforce traditional gender norms about the morality of sex: to discourage abortion, to allow antigay discrimination, and to “incentivize” heterosexual marriage.