Using recently released cohabitation data for the male sample of the National Longitudinal Survey of Youth, first interviewed in 1979, I conducted multinomial discrete-time event-history analyses of how young men's career-development process affects both the formation and the dissolution of cohabiting unions. For a substantial proportion of young men, cohabitation seemed to represent an adaptive strategy during a period of career immaturity, whereas marriage was a far more likely outcome for both stably employed cohabitors and noncohabitors alike. Earnings positively affected the entry into either a cohabiting or marital union but exhibited a strong threshold effect. Once the men were in cohabiting unions, however, earnings had little effect on the odds of marrying. Men with better long-run socioeconomic prospects were far more likely to marry from either the noncohabiting or cohabiting state, and this was particularly true for blacks.