IntroductionCocreation, coproduction and codesign are advocated as effective ways of involving citizens in the design, management, provision and evaluation of health and social care services. Although numerous case studies describe the nature and level of coproduction in individual projects, there remain three significant gaps in the evidence base: (1) measures of coproduction processes and their outcomes, (2) mechanisms that enable inclusivity and reciprocity and (3) management systems and styles. By focusing on these issues, we aim to explore, enhance and measure the value of coproduction for improving the health and well-being of citizens.Methods and analysisNine ongoing coproduction projects form the core of an interactive research programme (‘Samskapa’) during a 6-year period (2019–2024). Six of these will take place in Sweden and three will be undertaken in England to enable knowledge exchange and cross-cultural comparison. The programme has a longitudinal case study design using both qualitative and quantitative methods. Cross-case analysis and a sensemaking process will generate relevant lessons both for those participating in the projects and researchers. Based on the findings, we will develop explanatory models and other outputs to increase the sustained value (and values) of future coproduction initiatives in these sectors.Ethics and disseminationAll necessary ethical approvals will be obtained from the regional Ethical Board in Sweden and from relevant authorities in England. All data and personal data will be handled in accordance with General Data Protection Regulations. Given the interactive nature of the research programme, knowledge dissemination to participants and stakeholders in the nine projects will be ongoing throughout the 6 years. External workshops—facilitated in collaboration with participating case studies and citizens—both during and at the end of the programme will provide an additional dissemination mechanism and involve health and social care practitioners, policymakers and third-sector organisations.