Rates of posttraumatic stress symptoms (PTSS) are high among female survivors of intimate partner violence (IPV), and children of parents experiencing PTSS are at increased risk for emotional and behavioral problems. However, little is known about the factors that may explain this relation. We examined child's emotion regulation as a moderator and mother's emotion regulation as a mediator of the relation between mother PTSS and child adjustment. Sixty-four female survivors of IPV and their 6-12-year-old children participated. Mothers reported their own PTSS and their children's adjustment. Child emotion regulation was measured using respiratory sinus arrhythmia, a physiological index of emotion regulation. Mother's emotion regulation was measured from observer coding of the Parent Meta-Emotion Interview (Katz & Gottman, 1986), which asked mothers about their awareness and regulation of emotion. Child emotion regulation moderated the relation between mother's PTSS and child depression and child PTSS. Mothers' total trauma symptom severity showed significant indirect effects on children's internalizing, externalizing, and total problems via mothers' emotion regulation. Results suggest that children's as well as mothers' emotion-regulation abilities represent factors that affect associations between maternal PTSS and child adjustment in families exposed to IPV.