The electronic health record (EHR) is the primary tool through which clinicians interpret, create and curate patient data. However, EHR interfaces are criticised as unintuitive, cognitively burdensome and misaligned with the demands of clinical work. This thesis argues that the primary purpose of the EHR interface is not to support clinicians in what they do, but in how they think. EHR interfaces therefore can be considered to operate at the level of clinical sense-making—the process through which clinicians construct meaning from data— and need to be designed at that level. The challenge in this research is epistemic—understood as how knowledge is structured and made available to thought—and is approached through visualisation, which is well suited to representing data so that their relationships can be perceived, compared and interpreted. The research unfolded across three iterative cycles. Cycle 1 captured, elicited and articulated clinical sense-making knowledge embodied in single-clinician-designed EHR interface development artefacts (the STIQI paper sketches and v.1 prototype), deriving clinical sense- making insights and clinician-facing evaluative heuristics. These were incorporated into a mixed-methods survey to enable participatory engagement. Cycle 2 engaged the national integrated sexual health clinician community, deploying the survey across both the STIQI v.1 prototype and commercial EHR systems. Convergent quantitative and qualitative findings corroborated and stabilised clinical sense-making knowledge from Cycle 1 through recurring clinician themes. Cycle 3 explicitly re-specified this stabilised clinical sense-making knowledge into interface structure using the Representational Epistemic (REEP) approach to visualisation, producing a REEP-informed blueprint and redesigned prototype (STIQI v.2). These two epistemic artefacts enabled the stabilised knowledge to be applied, tested and refined within an interface environment, and formalised as a design framework for clinical sense-making in EHR interfaces. This research reframes clinical sense-making as the primary purpose of the EHR interface and positions visualisation as the representational form through which that purpose is realised. By identifying the challenge of EHR interface design as epistemic rather than technical, the thesis clarifies why usability- and technology-driven improvements have often struggled to address clinician concerns. The principal contribution of this thesis is the identification of longitudinal narrative coherence (LNC) as a foundational interface principle for supporting clinical sense-making. It is defined as the capacity of an EHR interface to represent a patient’s evolving story across time, data sources and clinical authorship, without compensatory mental reconstruction by the user. When LNC is not given explicit representational form within an interface, clinicians experience loss of orientation, reduced confidence and safety concerns. When instantiated, clinical data become perceptually grounded, temporally salient and intelligible. The operational contribution of this thesis is a design framework for clinical sense-making in EHR interfaces that operationalises LNC through eight clinical sense-making (CSM) commitments, design strategies, design constraints, failure modes and clinician-facing evaluative heuristics. The framework provides a transdisciplinary language through which clinical sense-making can be articulated, specified and evaluated within EHR interface design.