The Four Cs model offers a coherent way to diagnose and design improvement efforts within healthcare systems today

Significant and sustained change in healthcare is often challenging. One explanation is the need to satisfy many stakeholders who may have different interests. In the context of the Special Issue on improvement science, multiple and aligned changes at different levels are often needed to create genuine change. To propose ideas about why these types of change are hard to achieve, and present a model—a heuristic device—for guiding such change by those responsible for improvement in healthcare. Narrative review and conceptual synthesis. The author team combined (i) long-standing expertise in health system improvement and implementation science with (ii) targeted identification of relevant literature across complexity, organisational culture, context, and relational/coordination scholarship. We iteratively coded and clustered concepts, compared them with established improvement and implementation frameworks, and refined the model through consensus via a range of meetings and discussions of healthcare improvement over a ten-year period. The synthesis yields the Four Cs model—Complexity, Cultures, Contexts, and Connections—as a coherent way to diagnose and design improvement efforts. The model highlights the need for continual coordination across levels as contexts shift, and it reframes ‘change agents’ as ‘improvement architects’ who work deliberately with system dynamics, cultural patterns, contextual constraints, and relational coordination. The Four Cs model integrates four well-established constructs into an improvement science-oriented heuristic intended to support reflection, sensemaking, and design. We propose it as a practical guide and agenda for empirical testing, refinement, and debate within the improvement community.