The consequences of divorce are pronounced for parents of young children, and cohabitation dissolution is increasing in this population and has important implications. The mental health consequences of union dissolution were examined, by union type and parental gender, using the Fragile Families and Child Wellbeing Study (n= 1,998 for mothers and 1,764 for fathers). Overall, cohabitation and marital dissolution were both associated with increased maternal and paternal depressive symptoms, though for married mothers, depressive symptoms returned to predissolution levels with time. Difference-in-difference estimates indicated no differences in the magnitude of the increase in depressive symptoms by type of dissolution, though pooled difference models suggested that married fathers increased in depressive symptoms more than cohabiting fathers. Potential time-variant mediators did not account for these associations, though greater family chaos was associated with increased maternal depressive symptoms, and decreased social support and father–child contact were associated with increased paternal depressive symptoms.