Data from both waves of the National Survey of Families and Households (NSFH) were used to estimate the effects of couple-level measures of cohabitors' relationship assessments and expectations on their union transitions. Although positive relationship assessments deterred separation, they did not hasten entry into marriage. Female partners' negative assessments of the relationship increased the odds of separation, whereas such reports among male partners weakened the odds of marriage. Plans to marry were positively associated with marriage entry, but this effect was considerably larger for White couples than it was for Black couples. Cohabitors' expectations that their union would dissolve were also associated with union transitions. When both partners reported an even to high chance of dissolution, the odds of marriage were low, and the odds of separation were high. Cohabitors' own relationship assessments and expectations are significant predictors of their union outcomes.