The objective of this research is to contribute to knowledge and understanding by exploring: first, the professional identities of English General Practitioners (GPs) and other clinicians in the newly-formed Clinical Commissioning Groups (CCGs) and second, their level of involvement in CCG ‘calculative practices’ (Miller, 1990, 2001). The institutional field studied is acute care, i.e. hospital, commissioning in contemporary England. To achieve its objective, this thesis asks four research questions: 1) ‘How appropriate is it for clinicians to be involved in CCG acute care commissioning?’ 2) What motivates clinicians to assume leadership roles in CCGs?’ 3) How involved are clinicians in CCG calculative practices?’ and 4) To what extent do hybridity and calculative practices affect clinicians’ professional identities in CCGs?’ The theoretical framework used is based on the concept of ‘calculative practices’ and elements of the Institutional Logics Theory (ILT). This research employs three research methods – documents’ content analysis, semi-structured, in-person interviews, and non-participant observation of CCG meetings with the public and NHS conferences. The interview subjects are NHS managers and accountants, as well as clinicians. This thesis answers the four research questions and then proposes some additional, incidental to this research findings and contributions to policy/legislation and practice. In conclusion, this study deliberates on the viability of the purchaser-provider split of the early 1990s that established the foundations and raison d’être of CCG commissioning and dwells on the possibility that one day the general taxation-funded and free at the point of service National Health Service (NHS) in England may cede its way to a US-inspired model of full blown privatisation