Maternal interpersonal violence-related post-traumatic stress disorder (IPV-PTSD) is known to be associated with impairment of a mother's capacity to participate in mutual emotion regulation during her child's first years of life. This study tested the hypothesis that maternal difficulty in identifying feelings in self and other, as an important dimension of the construct of alexithymia, together with maternal IPV-PTSD, would be negatively associated with maternal sensitivity. Maternal sensitivity to child emotional communication is a marker of maternal capacity to engage in mutual regulation of emotion and arousal. Following diagnostic interviews and administration of the Toronto Alexithymia Scale, 56 mothers and their toddlers (ages 12-42 months) were filmed during free-play and separation/novelty-exposure. Observed maternal sensitivity was coded via the CARE-Index. Maternal IPV-PTSD severity, difficulty in identifying emotions, and lower socio-economic status were all associated with less maternal sensitivity, and also with more maternal controlling and unresponsive behavior on the CARE-Index.