Background: In the UK managers from multiple organisations are commonly tasked with collectively devising and implementing local health and wellbeing policies as a way of addressing increasing demand for healthcare. This requires them to create knowledge together but relatively little is known about how this occurs. This paper reports the results of research into how managers collectively create knowledge in order to address local health and wellbeing challenges. Methods: We undertook a case study in three sites in England. Using statistical network modelling we identified clusters of actors and interviewed managers from heterogeneous clusters about their collective activities. We used interview and documentary data to construct accounts of collective knowledge creation. Findings: Managers simultaneously work across stable bureaucratic networks and temporary taskforces in order to create and implement local health and wellbeing policy. They collectively create knowledge by enacting networks of relationships which enable them to share and build on routines and discourses and to reach out for new evidence, perspectives and skills. When creating knowledge, managers' ability to draw on and harmonise alternative programmes of action and their willingness to collectively negotiate is more important than their managerial status or position. Conclusions: Managers should be encouraged to examine and discuss their alternative programmes of action and to see these as a catalyst for rather than barrier to collectively creating and implementing local health and wellbeing policies, and should be supported and valued for their ability to harmonise conflicting programmes of action.