OBJECTIVE: The 2010 healthcare reform in England introduced primary care-led commissioning in the National Health Service (NHS) by establishing clinical commissioning groups (CCGs). A key factor for the success of the reform is the provision of excellent commissioning support services to CCGs. The Government's aim is to create a vibrant market of competing providers of such services (from both for-profit and not-for-profit sectors). Until this market develops, however, commissioning support units (CSUs) have been created from which CCGs are buying commissioning support functions. This study explored the attitudes of CCGs towards outsourcing commissioning support functions during the initial stage of the reform. DESIGN: The research took place between September 2011 and June 2012. We used a case study research design in eight CCGs, conducting in-depth interviews, observation of meetings and analysis of policy documents. SETTING/PARTICIPANTS: We conducted 96 interviews and observed 146 meetings (a total of approximately 439 h). RESULTS: Many CCGs were reluctant to outsource core commissioning support functions (such as contracting) for fear of losing local knowledge and trusted relationships. Others were disappointed by the absence of choice and saw CSUs as monopolies and a recreation of the abolished PCTs. Many expressed doubts about the expectation that outsourcing of commissioning support functions will result in lower administrative costs. CONCLUSIONS: Given the nature of healthcare commissioning, outsourcing vital commissioning support functions may not be the preferred option of CCGs. Considerations of high transaction costs, and the risk of fragmentation of services and loss of trusted relationships involved in short-term contracting, may lead most CCGs to decide to form long-term partnerships with commissioning support suppliers in the future. This option, however, limits competition by creating 'network closure' and calls into question the Government's intention to create a vibrant market of commissioning support provision.