Patient safety and providing a high quality of care are the prerequisite requirements for the effective and efficient operation of any healthcare organisation. However, alarming statistics of errors and adverse events continue to grow with effective organisational models to guide the reduction and control of error rates. The healthcare sector requires a major reform in current practices and the holistic approach known as High Reliability Organisation (HRO) offers potential utility when delivering error-free performance and reliable care and has evolved from studies of safety-critical environments, yet it has received little academic attention for the healthcare setting. Despite more than two decades of HRO research, there is still a research gap in understanding how healthcare organisations can embrace the principles of HRO and what these principles mean. This research explores the meaning of HRO for healthcare professionals. As such, this doctoral research aims to develop a HRO theoretical model to understand the concept of the HRO as it applied within the context of the Welsh NHS setting. Two research questions were crafted for this study: RQ1- What are the perceived organisational features that enable higher reliability in the healthcare context? RQ2 - How the perceived organisational features interact with each other to enable higher reliability in the healthcare context? The narrative literature review process allowed the synthesising of the HRO literature and identifying the key organisational features that can enable high reliability practices in the healthcare setting. The outcome of the literature review was a conceptual HRO model of six interrelated organisational features (forming eleven hypotheses). These concepts included the mindful leader, training, communication, trust, reporting, and safety culture. The study is framed using ‘sensemaking’ and ‘systems’ theories as explanators of the HRO healthcare model. An online survey instrument was designed to test the HRO theoretical model in the Welsh NHS setting. Clinical and managerial workers from four Health Boards/Trusts (259 usable responses) participated. Structured Equation Modelling (SEM) was used to test the HRO model. The findings show that staff define HRO as the technical and socio-aspects for achieving high reliability performance; the revised HRO model identified that mindful leaders have a direct and significant impact on communication, training, and feedback. The mindful leader indirectly impacts safety culture through the mediation effect of communication, reporting, and trust. The training was found to have a direct impact on building trust and establishing good communication and reporting across the organisation. The revised HRO model, as a result of this study, provides a contextually specific (healthcare) understanding of HRO that differs greatly from other safety-critical contexts. The findings of the study have significant managerial and policy implications for the promotion and increased awareness of HRO amongst healthcare professionals and how to engage professional clinicians and professional managers who see HRO in similar but distinct forms. The contribution of the study is a healthcare specific description of HRO as a means of achieving higher system reliability.