Using recently released cohabitation data for NLSY79 males, this study conducts multinomial discrete-time event history-analyses of how young men’s career development process affects both the formation and dissolution of cohabiting unions. For a substantial proportion of young men, cohabitation seems to represent an adaptive strategy during a period of career immaturity, as measured by employment instability, while 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 and exhibited a strong threshold effect. However, consistent with a selectivity argument, once cohabiting, earnings had little effect on the odds of marrying out of a cohabitation although higher earnings did discourage separations among whites. Men with better long-run socioeconomic prospects, i.e., the college educated, were far more likely to marry from either the noncohabiting or cohabiting state and this was particularly true for blacks.