This study investigated the socialization of children's emotion regulation in 25 physically maltreating and 25 nonmaltreating mother–child dyads. Maltreating mothers and their 6- to 12-year-old children were recruited from two parenting programs affiliated with Children's Protective Services with a control group matched on race, SES, child gender, and child age. Children and their mothers were interviewed individually about their (a) management of emotional expression, (b) strategies for coping with emotional arousal, and (c) anticipated consequences following emotional displays. Compared to controls, maltreated children expected less maternal support in response to their emotional displays, reported being less likely to display emotions to their mothers, and generated fewer effective coping strategies for anger. Maltreating mothers indicated less understanding of children's emotional displays and fewer effective strategies for helping children to cope with emotionally arousing situations than nonmaltreating mothers. Further, findings indicated that maternal socialization practices (e.g., providing support in response to children's emotional display, generating effective coping strategies for their child) mediate the relation between child maltreatment and children's regulation of emotional expression and emotional arousal. These findings suggest that children's emotion regulation strategies are influenced by their relationship with their social environment (e.g., physically maltreating, nonmaltreating) and that the experience of a physically maltreating relationship may interfere with children's emotional development.