The use of contracts is vital to market transactions. The introduction of market reforms in health care in the U.K. and other developed countries twenty years ago meant greater use of contracts. In the U.K., health care contracting was widely researched in the 1990s. Yet, despite the changing policy context, the subject has attracted less interest in recent years. This paper seeks to fill a gap by reporting findings from a study of contracting in the English National Health Service (NHS) after the introduction of the national standard contract in 2007. By using economic and socio-legal theories and two case studies we examine the way in which the new contract was implemented in practice and the extent to which implementation conformed to policy intentions and to our theoretical predictions. Data were collected using non-participant observation of 36 contracting meetings, 24 semi-structured interviews, and analysis of documents. We found that despite efforts to introduce a more detailed ('complete') contract, in practice, purchasers and providers often reverted to a more relational style of contracting. Frequently reliance on the NHS hierarchy proved to be indispensable; in particular, formal dispute resolution was avoided and financial risk was re-allocated in compromises that sometimes ignored contractual provisions. Serious data deficiencies and shortages of skilled personnel still caused major difficulties. We conclude that contracting for health care continues to raise serious problems, which may be exacerbated by the impending transfer of responsibility to groups of general practitioners (GPs) who generally lack experience and expertise in large-scale, secondary care contracting.