The aim of this study was to examine associations between maternal mentalization, interactive behavior, and child symptoms in families in which mothers suffer from interpersonal violence-related posttraumatic stress disorder (IPV-PTSD). Fifty-six mothers and children (aged 12-42 months) including mothers with a diagnosis of IPV-PTSD were studied. Mentalization was measured by the Parental Reflective Functioning (PRF) Scale. Interactive behavior during free-play was measured via the CARE-Index. Child symptoms were measured by the Infant-Toddler Social and Emotional Assessment (ITSEA). Data analyses included non-parametric correlations and multiple linear regression. Results showed that lower IPV-PTSD and higher Maternal Reflective Functioning (MRF) were related to greater maternal sensitivity. Lower MRF and greater controlling behavior were related to child dysregulation. MRF was found to be lower in the subgroup of IPV-PTSD when the child's father was the perpetrator of IPV. Both MRF and interactive behavior are thus likely to be important targets for intervention during sensitive periods of early social-emotional development.