This article discusses the case of Christina and Bobby, who were treated in the context of the Project for Mothers, Infants, and Young Children of September 11, 2001. It considers how Bobby's inconsolable distress may have contributed to the reactivation of the mother's traumatic memories. Scheeringa and Zeanah's relational PTSD model is used to consider how this mother may have mediated and/or moderated Bobby's experience of trauma. The significance of affect contagion as a mediator of trauma, particularly the relevance of mirror neurons, is discussed. A psychodynamic perspective on Christina's experience of her own mother's intrusion and how this may have affected her relationship with her son is considered. The power of video feedback therapy and the urgency of mother-infant treatment are noted.