Objective: To develop a substantive grounded theory that explains how nurses in acute frailty units construct, negotiate, and enact evidence-based practice (EBP) in everyday care.

Methods: A constructivist grounded theory design guided 21 interviews and 36 hours of focused observation in an English acute frailty unit. Analysis used initial and focused coding, theoretical coding, and memoing, supported by supplementary situational mapping to sensitise contextual relations. Constant comparison informed category development and specification of the core process.

Results: The basic social process, constructing situated EBP, comprised four linked practices: negotiating professional boundaries, integrating patient and family preferences, mediating organisational pressures, and sustaining professional identity. Credible proposals gained traction through strategic timing, relational framing, use of visible warrants such as validated tools and audit indicators, and the adoption of locally recognised institutional language. These brief, distributed moves functioned as micro-facilitation, enabling bedside nurses to align patient goals with organisational imperatives and to document rationales that colleagues could accept under constraint.

Conclusions: The theory explains how nurses translate shared evidence into situated action within fast-paced multidisciplinary forums. It extends implementation accounts by specifying micro-facilitation as routine interactional work rather than a discrete role, and by showing how proposals that link patient priorities to organisationally legible indicators support safe, acceptable decisions under flow pressure. The model is transferable to high-tempo services managing multimorbidity where teams rely on a small set of legitimising tools and rapid deliberation.