Community pharmacies offer opportunities to deliver preventive care to populations experiencing geographical, financial, cultural, linguistic and organizational barriers to healthcare. However, service availability, initial attendance and sustained participation represent different outcomes. Understanding how outreach influences these outcomes requires attention to the circumstances in which services operate and the reasoning of people who encounter them. To examine how, why, for whom and under which circumstances community pharmacy outreach supports engagement and sustained participation in preventive care, with particular attention to relational trust, service accessibility and interprofessional partnerships. A realist review approach was developed around initial programme theory, iterative evidence identification, relevance and rigour appraisal, and context–mechanism–outcome analysis. Public literature discovery and preliminary evidence mapping identified candidate publications addressing pharmacy access, preventive services, underserved populations and interprofessional collaboration. The available search record did not establish a complete, deduplicated and eligibility-screened evidence set. Preliminary evidence mapping identified explanatory questions concerning whether outreach resources are perceived as credible, practically usable and connected to subsequent care. The proposed analytical distinctions concern initial contact, preventive-service uptake, completed referral, follow-up and sustained participation. Formal evidence-supported context–mechanism–outcome configurations and final included-evidence counts remain unestablished. A realist explanation of pharmacy outreach must account for how service resources interact with social circumstances, professional relationships and organizational arrangements. Its claims concerning sustained participation require longitudinal evidence and a completed, transparent synthesis.
