Between 1975 and 1995, the singulate mean age at marriage in Japan increased from 24.5 to 27.7 years for women and from 27.6 to 30.7 years for men, making Japan one of the latest-marrying populations in the world. Over the same period, the proportion of women who will never marry, calculated from age-specific first-marriage probabilities pertaining to a particular calendar year, increased from 5 to 15 percent for women and from 6 to 22 percent for men—behaviors sharply different from those characterizing the universal-marriage society of earlier years. This article investigates how and why these changes have come about. The reasons are bound up with rapid educational gains by women, massive increases in the proportion of women who work for pay outside the home, major changes in the structure and functioning of the marriage market, extraordinary increases in the prevalence of premarital sex, and far-reaching changes in values relating to marriage and family life.