Abstract Background Research indicates that Posttraumatic stress disorder (PTSD) has an extensive impact on family relationships. Nevertheless, there is a dearth of empirically supported interventions addressing family functioning and PTSD. In the Netherlands, it is considered good clinical practice to offer multi-family therapy (MFT) to veteran and refugee families. MFT for traumatized families aims to address the dysfunctional family patterns that have evolved to address the consequences with trauma. Method The aim of this study is to generate a common framework for the practical impact and active ingredients of MFT in families confronted with trauma. The Delphi method was used to study the expert opinion of 11 therapists in Dutch expert trauma institutes. Results The results indicate that MFT is a promising treatment for families dealing with the consequences of trauma. According to experts, positive outcomes include an increased understanding between family members, particularly visible in the de-escalation of conflicts within the family, and improved parenting. One explanation for the effectiveness of MFT with these target groups is its defining feature of therapy with several families. Conclusions The findings support the importance of considering family relationships and the family context in interventions for traumatized individuals.