Concept and aim: 20 million fans attend top division football games each week and many more watch on TV. Our social innovation is to attract people to lifestyle change through the personal connection and loyalty to the club they support. Our aim is to use this social innovation to change physical activity and sedentary behaviour, specially targeting low-SES groups, and men as well as women. EuroFIT is supported by UEFA and top football clubs.Workplan: End-users and policy-makers are involved throughout. We will: a) produce a device (SitFIT) that provides real-time feedback on objectively measured sedentary time and physical activity; b) deploy and evaluate smartphone games to drive activity through social interaction (MatchFIT); c) integrate these with state-of-the-art evidence on behavioural change and its maintenance in a web-supported lifestyle programme delivered by top EU football clubs (EuroFIT)). We will evaluate EuroFIT in a multi-centre randomised controlled trial to assess impact on physical activity and sedentary behaviour, physical and mental health and weight. We will investigate the correlates of long-term changes and impact on participants’ families. Finally we will develop a robust strategy for replication of EuroFITImpact: We will generate excellent research evidence on the use of social innovation for health. Social impact will include reductions in health risk, improvements in well-being and the decreased inequalities as more men, especially those in low SES groups, are attracted to lifestyle change. Research impact will be achieved through new understanding of the how health indicators respond to change in sedentary behaviour and physical activity and through new knowledge of longterm maintenance of lifestyle changes. Policy impact will result from the production of clear implementation strategies and involvement of policy makers and opinion leaders from the outset, supported by a targeted communication strategy.