Background: Child Maltreatment is a concerning worldwide problem. The population of distressed mothers with their highly disturbed children, in middle-childhood, often present to child and adolescent mental health services (CAMHS). Finding effective therapies for this population has proved elusive. This led the authors to undertake a theory-driven research program to better understand intergenerational child maltreatment from a clinical perspective, in order to determine how best to treat the entrenched distressing and destructive behaviors.Methods: The model describing the mechanisms of the intergenerational transmission of maternal maltreatment is briefly described, from which the objectives of any effective treatment for these mothers and children are derived. A clinical model for achieving the therapeutic objectives is then elucidated.Findings: Core objectives of therapy are; first to support the mother and child to develop differentiated senses of self and, second to disrupt a relationship style built on a competitive dominance and submission hierarchy, replacing it with a hedonic (cooperative and compassionate relationship style). This requires a deep healing of the mother and child's trauma histories. A clinical operationalization of these objectives, through a novel dyadic psychotherapeutic protocol, Parallel Parent and Child Therapy is described, which addresses the therapeutic objectives while attending to the safety of mother and child.Interpretation: This research contributes to a better understanding of the components of effective treatment in what is a notoriously hard to treat population. It also illustrates the value of clinically informed theory development in understanding and refining treatment strategies for highly distressed and distressing populations.