Background: The treatment of pain in children is a universal and fundamental right. Despite the growing evidence relating to postoperative pain management in children and relevant practice guidelines, children still experience moderate to severe pain after surgery. Whilst there are multiple reasons why postoperative pain management practices remain suboptimal, one possible factor could be related to the relatively unexplored interaction between children, parents, and nurses whilst in hospital. Aim: This study aimed to explore the interactions between children (aged 6-11 years old), their parents and nurses during postoperative pain management and construct a theory of this interaction. Methodology and Methods: A qualitative constructivist grounded theory methodology was used. Data were collected from four surgical wards in a paediatric hospital in England. Thirty-three face-to-face semi-structured interviews were conducted with 10 children, 11 parents and 10 nurses. Eligible participants were recruited through purposive sampling and theoretical sampling until theoretical saturation was reached. Data were analysed using constant comparison technique, memos, and constructivist grounded theory coding levels. Results: The grounded theory, âFacilitating or Inhibiting Interactions: Parental Influence on Postoperative Pain Managementâ, constructed from the data consists of a core category, âChild-nurse interaction via parentâ, and its two overlapping subcategories, âParent-nurse dyadic interactionâ and âChild-parent dyadic interactionâ. The theory provides a theoretical understanding of children's postoperative pain management in relation to child-parent-nurse interactions in hospital. The findings highlight an absence of a three-way interaction between children, parents, and nurses and an expected dyadic interaction process between children and nurses was not apparent. The findings, therefore, suggest that child-parent-nurse interactions were constructed around two dyads of child-parent and parent-nurse interactions with child-nurse interaction constructed via parents. Parents, as the chosen communicator by children and nurses, managed the child-nurse interaction by oscillating between these two dyads. Parents continuously moved between dyads and became the only group involved in all interaction processes of postoperative pain management. Parents, as a result, influenced the entire postoperative pain management processes between children, parents, and nurses by facilitating or inhibiting the interaction processes. Conclusion: This study highlights the complexity and multidimensionality of child-parent-nurse interactions and suggests that parents play a central communicator role in child-nurse interaction during postoperative pain management, however, this is a combination of groups of two-way rather than a three-way interaction. The constructed grounded theory suggests a theoretical framework for nursing postoperative pain management practices with children in the presence of parents. This theory also has important implications for future research, wider society, and policy.