{Reference Type}: Journal Article {Title}: Advancing Nursing Science: Deriving a Middle-Range Theory for System-Level Communication Research in Complex Hospital Environments. {Author}: Brittain AC;Carrington JM; {Journal}: Res Theory Nurs Pract {Volume}: 38 {Issue}: 2 {Year}: 2024 Apr 25 {Factor}: 0.745 {DOI}: 10.1891/RTNP-2023-0092 {Abstract}: Background: Millions of injuries and deaths occur yearly from preventable errors, despite interventions applied at the point of care. Although evidence suggests that system-level factors are responsible for hospital system health and patient safety, research has largely not accounted for hospital complexity. Prior to the authors' research regarding the communication of system-level events that influence hospital system health and patient safety, no nursing-specific communication theories that accounted for hospital complexity were identified. However, theory-guided research holds the potential to boost scientific knowledge through the provision of a robust foundational understanding of phenomena. Purpose: The purpose of this article is to discuss the concept derivation used to create a middle-range theory for the guidance of research involving system-level communication in complex healthcare environments as it relates to hospital system health and patient safety. Methods: Concept derivation as described by Walker and Avant (2018) was conducted using parent concepts from the Effective Nurse-to-Nurse Communication Framework, Symbolic Interactionism, Information Theory, Gerbner's Communication Model, and Complexity Theory. Results: Authentication of the derived Effective System-to-System Communication Theory (ESSCT) was confirmed through identification of coherent relationships between the concepts and conceptual statements, alignment with the nursing metaparadigm, and peer review by a subject matter expert from the nursing discipline. Additionally, research revealed an overall congruency between the research findings and the ESSCT's theoretical statements. Implications: The current healthcare climate necessitates that research involving communication be optimized by a germane theoretical underpinning that accounts for hospital complexity. The authors contend that the use of the derived theory may assist such endeavors.