Introduction The impact of contextual factors on primary health-care quality improvement is significant. In-depth research is required to identify the key contextual factors that influence quality improvement initiatives to develop high-performing primary health-care systems. Aim This research seeks to answer two questions; what are the contextual factors influencing primary care improvement initiatives?; and how do contextual factors, the quality improvement initiative and the implementation process influence one another and the overall improvement outcomes? Methods A multi-case study methodology was used to explore the complexities of the phenomena in situ . Three sites where successful quality improvement had occurred were selected by purposeful theoretical sampling to provide a sample of rural, urban and Kaupapa Māori general practice settings typical of the New Zealand environment. Semi-structured interviews were conducted with team members and triangulated with secondary data provided by the organisations. Results The quality improvement topic and the approach taken were intrinsically linked to context. Sites reported success in achieving the desired outcomes benefitting the patients, practice and staff. Teams did not use formal improvement methods, instead relying on established relationships and elements of change management methods. The culture in all three cases was a large component of why and how these initiatives were successful. Discussion Intrinsic motivation was generated by community connections and networks. This combined with a learning climate generated by distributed leadership and teamwork enabled success. Iterative reflection and sensemaking processes were able to deliver quality improvement success in primary care without the use of formal improvement methods.