The aim of this research was to explore the factors that influence the implementation of pharmacist prescribing in secondary care. A two-phased, mixed methods study was conducted. The first phase comprised a small qualitative study to investigate the views of clinicians, patients and NH5 managers and a survey of doctors, nurses and pharmacists to quantify those views. It was conducted in one NHS trust before pharmacist prescribing had been introduced. In the second phase, which used documentary analysis, focus groups and interviews, case studies of non-medical prescribing implementation were carried out in five hospital trusts. Factors identified in the first phase qualitative study, included the attitudes of clinical staff and patients, and adequacy of resources. Pharmacists were perceived by some stakeholders to be "drug experts" but there were reservations about their diagnostic skills and not "knowing" a patient in the same way as doctors and nurses do. The survey showed different levels of support for pharmacist prescribing from doctors (58%), nurses (68%) and pharmacists (96%). Nurses (40%) were more supportive of pharmacist independent prescribing than doctors (18%) but were more likely to support prescribing roles for themselves than pharmacists. The case studies found that experiences from 'doing' pharmacist prescribing became influential in shaping professional views of whether and how implementation should proceed. Views from the two phases overlapped but some differences emerged between the more theoretical considerations in the first phase of the research and experiential learning in the second, concerning, for example, the relative merits of supplementary and independent prescribing. A model by Greenhalgh et al (2004) of adoption of innovations proved useful in understanding the complexity of how and why there was mediation of the effects of the different factors. How factors influenced implementation varied according to culture/context/policy at a micro- and a macro- level.