Using six waves of panel data from the Fragile Families and Child Wellbeing Study (N =1,768), this study explores the relationship between maternal education after first birth and coresidential stability among urban couples in the United States. The proportional hazards model is utilized to study the impact of postnatal education on union dissolutions. The preliminary results suggest that (1) mothers who completed or obtained additional education after first birth are at least 67% less likely (p < 0.01) to separate with their partners compared to mothers without postnatal education after isolating the effect of key demographics, economic, and relational factors. (2) Married couples compared to cohabiting couples are 38% less likely (p <0.01) to separate with or without postnatal education holding all else constant. The significant association of postnatal education and union stability suggests that postnatal education improves union stability, but the association may also be mediated by mate selection process and other unaccounted factors.