This study focused on the interrelations among different domains of maternal adaptation (i.e., emotion-regulation difficulties, depressive symptoms, and couple-relationship satisfaction) over the transition to parenthood and also their associations with mothers’ recalled childhood maternal nonsupportive emotion socialization. Data were obtained from a socioeconomically and racially diverse sample of 196 primiparous mothers during the 3rd trimester of pregnancy and at 6 months postpartum. Results indicated that (a) mothers’ adaptation in different domains had shared roots in their recalled childhood maternal nonsupportive emotion socialization; (b) maternal adaptation in various domains were interrelated with rather than independent of each other, and such associations were unidirectional rather than reciprocal (e.g., mothers’ prenatal couple-relationship satisfaction was negatively associated with their depressive symptoms at 6 months postpartum rather than the reverse); and (c) mothers’ adaptation in a given domain served as the mechanism via which their recalled childhood maternal nonsupportive emotion socialization shaped their adaptation in the other domains (e.g., mothers’ recalled maternal nonsupportive emotion socialization was positively associated with their depressive symptoms at 6 months postpartum via its positive association with their prenatal emotion-regulation difficulties). These associations were independent of several critical covariates (e.g., child negative affect, maternal attachment). Such findings contribute to a more nuanced understanding of the complexity inherent within maternal adaptation over the transition to parenthood and highlight potential avenues for interventions aimed at promoting mothers’ successful navigation of challenges over this transition.