This paper explains the reasons and context behind the introduction of the Quality and Outcomes Framework (QOF) in the UK in April 2004. The QOF is a pay-for-performance scheme covering a range of clinical and organisational areas in primary care. In 2004, 52% of the framework related to clinical care, increasing to 66% in 2006 and 70% in 2009. From April 2009, the National Institute for Health and Clinical Excellence (NICE) has led a new process for developing the clinical QOF indicators. Clinical areas are now prioritised by an advisory committee appointed by NICE; the QOF indicators then undergo a formal consensus procedure followed by piloting in representative practices across England. However, what are the attributes of a good QOF indicator and how do these differ from those of a good quality indicator, such as validity and sensitivity to change? This paper describes the concept of 'QOFability', which relates to why some areas are, and others are not, prioritised for the QOF. Factors include the prevalence of the clinical issue, the accuracy of data extraction from GP clinical systems, the clarity of diagnosis, the relevance of incentivised actions, the direct attribution to all primary care staff and consideration of any possible unintended consequences of introducing any given indicator. The paper concludes by considering the future direction of the QOF, recommending a focus on creating feasible, valid, reliable and piloted 'QOFable' clinical indicators.