BACKGROUND: This paper presents the results of the first UK-wide survey of National Health Service (NHS) general practitioners (GPs) and practice managers (PMs) designed to explore the service improvement activities being undertaken in practices, and the factors that facilitated or obstructed that work. The research was prompted by growing policy and professional interest in the quality of general practice and its improvement. The analysis compares GP and PM involvement in, and experience of, quality improvement activities. METHODS: This was a mixed-method study comprising 26 semistructured interviews, a focus group and two surveys. The qualitative data supported the design of the surveys, which were sent to all 46 238 GPs on the Royal College of General Practitioners (RCGP) database and the PM at every practice across the UK (n=9153) in July 2017. RESULTS: Responses from 2377 GPs and 1424 PMs were received and were broadly representative of each group. Ninety-nine per cent reported having planned or undertaken improvement activities in the previous 12 months. The most frequent related to prescribing and access. Key facilitators of improvement included 'good clinical leadership'. The two main barriers were 'too many demands from external stakeholders' and a lack of protected time. Audit and significant event audit were the most common improvement tools used, but respondents were interested in training on other quality improvement tools. CONCLUSION: GPs and PMs are interested in improving service quality. As such, the new quality improvement domain in the Quality and Outcomes Framework used in the payment of practices is likely to be relatively easily accepted by GPs in England. However, if improving quality is to become routine work for practices, it will be important for the NHS in the four UK countries to work with practices to mitigate some of the barriers that they face, in particular the lack of protected time.