Abstract: Grounded theory methodology has guided the grounded theory methods used to explore the acute care paediatric nurses' perspective of what they do when a child has had a severe accident. The research was initiated from the experience of nursing children in the context of a rehabilitation centre and wondering how acute care nurses promoted a child's recovery after a severe unintentional injury. Many avenues were used to search international and New Zealand literature but the scarcity of literature related to what acute care paediatric nurses do was evident. Nursing children in the acute care ward after a severe accident is complex. It encompasses nursing the family when they are experiencing a crisis. It is critical that the acute care nurse monitors and ensures the child's physiological needs are met, and the nurse “works with” the child to maintain and advance medical stability. Nursing interactions are an important part of “working with”, communication is the essence of nursing. This research has focussed on the nurses' social processes whilst caring for the physical needs of the child and interacting with the family and multidisciplinary team when appropriate. An effective working-relationship with a nurse and family is founded on trust. Grounded theory methods supported the process of exploring the social processes of “building trust” whilst “working with” families in a vulnerable position. Nurses rely on rapport to be invited into a family's space to “work with” and support the re-establishment of the parenting role. The “stepping in and out” of an effective working-relationship with a family is reliant on trust. Nurses build trust by spending time to “be with”, using chat to get to know each other, involving and supporting the family to parent a “different” child and reassuring and giving realistic hope to help the child and parents cope with their changed future. A substantive theory of the concept of “building trust to work with” has been developed using grounded theory methods. The theory has been conceptualised using the perspective of seven registered nurses working in paediatric acute care wards that admit children who have had a severe traumatic accident.