Moving is a common experience for U.S. families and may negatively affect the mental health of both parents and children. In this study, we examined how residential mobility is associated with changes in mental health over time among mothers and children in the Future of Families and Child Wellbeing Study (previously "Fragile Families") from the child's birth to age 15. Using path analyses, we found that moving frequently when children were young was associated with greater depression among mothers when their children were 5, which, in turn, was associated with maternal and child mental health outcomes in the middle childhood and adolescent periods. That is, maternal depression acted as a pathway through which early residential mobility was associated with both maternal and child outcomes over time. This study highlights the complex interplay between residential mobility and maternal and child mental health and the critical role of maternal depression. Results underscore the need to support mothers who move frequently to support their own and their children's mental health in the years to follow. (PsycInfo Database Record (c) 2025 APA, all rights reserved).