Longitudinal pathways between maternal mental health in infancy and offspring romantic relationship outcomes in adulthood were examined using a 30-year prospective longitudinal study of 196 mothers and their children. Structural equation modeling revealed that maternal mental health at 30 months was related to offspring relationship status and relationship attachment insecurity at 30 years. The adolescent variables of offspring mental health and parental relationship status mediated the link between maternal mental health and offspring relationship status. In addition, adolescent mental health and family conflict mediated the pathway between maternal mental health and offspring attachment insecurity. These results highlight the importance of individual and parental mental health to romantic relationship outcomes, and emphasize the value of taking a developmental approach to the study of romantic relationships.