Coping with a child’s psychiatric disorder involves various challenges for parents that can result in family burden. One factor related to family burden, which has been examined in previous studies, involves the interaction of the parent with the child diagnosed with the disorder. The current study, expanding on this notion, examined the interactions between parents and two of their children, one with a disorder and one without, by assessing parental expressed emotion (EE). The study also assessed the relations between the interactions with each child, examining whether these two interactions were positively or negatively-related: the “spillover hypothesis” and the “compensation hypothesis,” respectively. In addition, the current study examined a mediation model whereby parental competence would mediate the association between parental EE towards each child and perceived family burden. 41 parents, whose children were treated at a mental health center, participated in the study. The Five Minute Speech Sample was administered to the parents to assess parental EE, as well as scales of parental competence and family burden. Results showed positive correlations between parental EE towards the two children (in the relationship and warmth subscales). The mediation model was confirmed only with regard to parental EE (relationship subscale) towards the child with the disorder. These findings support the spillover hypothesis, according to which feelings and cognitions are transferred from one family subsystem to another. Findings also highlight the importance of sense of competence in parenting a child with a psychiatric disorder, as it reduces family burden.