This article proposes a four‐factor outcome model for case management services with children and families when the children have experienced complex trauma. The factors are relationships between service users and practitioners, personal characteristics of service users and practitioners, social service system influences, and external influences. The model is based upon research on the common factors model of psychotherapy outcomes, research that the first author conducted on case management services with children and families who have experienced complex trauma, the authors' practice experience with children and families who have experienced complex trauma, related research and theory, and ideas from evidence‐based practice. While the model is tailored to family case management, we believe it is applicable to other domains of social services, such as family and couples therapy, child and family mental health, family advocacy, and family policy formulation and evaluation.