Aim: Lower limb amputation is an increasingly prevalent surgical procedure in the Western world due to the increase of peripheral vascular disease. Not everyone who receives a prosthetic limb will benefit from its use and may abandon this expensive technology, a move which may negatively effect their adjustment to the amputation and also impact on their quality of life. There is currently no consensus on the most important outcomes to measure in lower limb prosthetic rehabilitation, or on the specific outcome measures to be consistently used in prosthetic rehabilitation. The aim of this research is to explore ways to optimise lower limb prosthetic prescription by identifying and gaining a consensus on 1) the most important outcomes of prescription, 2) the most important predictors of prosthetic use, and 3) the most important factors which have an effect on optimising use of the prosthesis. Method: This is a mixed methods study. Repertory grid interviews were conducted with 2 lower limb prosthesis users to explore the values and preferences that prosthetic users have of their prosthetic devices; to investigate users’ perceptions of alternative prosthetic options and to demonstrate a novel method for exploring the values and preferences of lower limb prosthetic users. Semi-structured interviews were undertaken with 12 multidisciplinary service-providers within the amputation rehabilitation setting, and 6 focus groups were completed with 24 prosthesis users to identify the outcomes and predictors of prosthetic prescription from both the patient and professional perspective. This data was then used to create a Delphi survey of 23 experts within the amputation and prosthetic field, including users, service providers and academics, to develop a consensus on the most important factors to address within the prosthetic prescription process. Findings: The repertory grid interviews highlighted the need to include patient choice and opinion in the prosthetic prescription process, while the focus groups and interviews identified the outcomes and predictors of prosthetic prescription while ascertaining what other factors affect optimal use of the prosthesis. These factors were physical, psychological and social in nature, and in particular, showed how service provision affects optimal use. A consensus on the most important factors to address in the fitting process and service was then established in the Delphi study. Conclusion: By combining user and practitioner knowledge throughout the study, this research has developed a list of the essential elements to be monitored and improved in prosthetic prescription to improve outcomes, as well as highlighting the importance of patient inclusion and choice within the rehabilitation setting. This research indicates how fitting centres can potentially improve the service with the hope of improving fitting rates and user satisfaction and reducing the waste of medical resources.