Political devolution allowed policy divergence around the UK. But England, Scotland and Wales must coexist within the UK, which means that the overarching rules of devolution shape their policy options. What friction emerges, what does it mean for health and how does the UK deal with it? This article, based on extensive elite interviewing, identifies 'bottom-up' issues in which health policy divergence creates intergovernmental friction and 'top-down' issues in which broader conflicts affect health. The rest of the article identifies and explains the mechanisms of coordination and dispute resolution,finding them probably inadequate to managing conflict.