Background: We examined ecological (family socioeconomic status (SES)) and bioregulatory (sleep duration, sleep efficiency) moderators of the link between maternal psychological control and children's vulnerability to internalizing symptoms. Method: A large socioeconomically diverse sample of third graders (N = 141) and their mothers participated. Sleep was examined via actigraphy for one week. Psychological control and internalizing symptoms (depressive symptoms, anxiety symptoms, pre-sleep arousal) were examined through children's reports. Results: For children with poorer sleep, lower SES, or a combination of the two, maternal psychological control was positively related to depressive symptoms; this association was not evident for children with both better sleep and higher SES. Further, maternal psychological control, sleep efficiency, and SES interacted to predict both anxiety symptoms and pre-sleep arousal. Children were protected from the negative effects of psychological control when they were from higher SES families and had higher sleep efficiency; for all other groups of children, psychological control was associated with anxiety symptoms. A similar but less robust pattern of results was found for pre-sleep arousal. Conclusions: Findings highlight the importance of children's bioregulatory processes within the socioeconomic context for an enhanced understanding of children's vulnerability to internalizing problems in the context of maternal psychological control.