Summary In health promotion programmes (HPP), it is crucial to have intersectoral collaboration within coalitions and to build networks between health and other societal sectors. A health broker role is recognized as being helpful in connecting the coalition with the broader network, and participatory action research (PAR) is deemed supportive because it facilitates evaluation, reflection, learning and action. However, there is a lack of insight into how processes that affect collaboration develop over time. Therefore, this study aimed to provide insights into the coalition’s processes that facilitate building and maintaining intersectoral collaboration within a HPP coalition and network and how these processes contribute to the coalition’s ambitions. As part of PAR, the coalition members used the coordinated action checklist (CAC) and composed network analysis (CNA) in 2018 and 2019. The CAC and CNA results were linked back into the coalition in five group sessions and used for reflection on pro-gress and future planning. Coalition governance, interaction with the context, network building and brokerage, and generating visibility emerged as the most prominent processes. Important insights concerned the health broker’s role and positioning, the programme coordinator’s leadership and the importance of visibility and trust leading to investment in continuation. The combined research instruments and group sessions supported discussion and reflection, sharing visions and adjusting working strategies, thereby strengthening the coalition’s capacity. Thus, PAR was useful for evaluating and simultaneously facilitating the processes that affect collaboration.