The prescribing rights of non-medical healthcare professionals in the United Kingdom (UK) are some of the most extensive in western medical practice. Nurses, pharmacists, physiotherapists, optometrists, chiropodists, podiatrists, therapeutic and diagnostic radiographers and dieticians, with appropriate training have the authority to prescribe. They are often referred to as non-medical prescribers (NMPs). These non-medical healthcare professionals should have a specified number of years of post-registration experience in order to undertake specific training in prescribing. There has been a limited amount of research exploring how non-medical healthcare professionals acquire their expertise during the prescribing programme. In addition, there is a gap in the literature on how NMPs apply their acquired expertise during the process of making clinical prescribing decisions. A programme of research was conducted to explore the learning processes and decision-making skills of pharmacist and nurse independent prescribers working in secondary care. The research used current literature on pharmacist and nurse independent prescribing by conducting a systematic review to assess how their expertise development is reported in the literature. In addition, the learning experiences of secondary care pharmacists and nurses undertaking the independent prescribing programme was explored by employing a novel audio-diary technique followed by semi-structured interviews on 7 nurses and 6 pharmacists. Students were mainly recruited via their non-medical prescribing programme leaders at a number of accredited universities across the UK. There was little opportunity in this study to explore the clinical reasoning processes of students as they were learning to prescribe. Therefore, the final study aimed to explore how secondary care pharmacist and nurse independent prescribers make clinical prescribing decisions. A total of 21 independent prescribers working in secondary care took part in this study, mainly recruited via their non-medical prescribing lead and social media. This study employed a think-aloud protocol method using validated clinical vignettes followed by semi-structured interviews. Students and NMPs occupied a wide range of roles. Ethical approval from the University of Manchester Research Ethics Committee (UREC) and governance approvals from a number of National Health Service (NHS) hospitals were obtained before conducting the research. NMPs were influenced by a number of intrinsic and extrinsic factors during the process of learning to prescribe and when making prescribing decisions. Students also experienced an affective phase of transition in which students became highly metacognitive as they began to form their identities as prescribers and reflect on their confidence and competence. There were notable differences between how pharmacists and nurses learned to prescribe, which were also seen during the process of clinical decision-making as independent prescribers. Despite this, pharmacists and nurses revealed a similar pattern in their decision-making processes as prescribers. Findings from this programme of research provide further insight into the specific training and support requirements of these healthcare professionals. Additional research with NMPs would be beneficial to contribute to the currently limited understanding of the learning and clinical reasoning processes of NMPs.