The MotC formulation-based approach is about making sense of the life, history, environment and social situation of parent and child—building a credible explanation of a ‘relationship-in-context’ rather than making general pronouncements based upon a classification. Only when applied to a specific relationship and social context does an attachment or caregiving classification have meaning and practical utility. This chapter outlines a 9-stage process to help develop a working explanation of what is going on in a parent-child relationship, how it might have come about, what is keeping the current pattern alive, and how it might be changed. The outcome of this process should be a credible and compassionate explanation of the key processes in the parent-child relationship, supported by the evidence in the transcript, and integrated with known history and other observations. It should articulate parental hopes and intentions, as well as the consequences for the child, situating them within the localised web of social relationships, in which the parent and child participate. Key principles for intervention based on this are outlined, including facilitating safety, managing arousal, exploring context, tailoring intervention to the level of defensive exclusion, and engaging protective caregiving.