The differentiated integration literature has developed from focusing on the varied nature of integration between EU Member States (internal) to considering the level of integration with non-EU states (external). Within a multi-level governance environment, differentiated integration opens up spaces for policy actors to form networks at the sub-state level. However, the scope of integration in these networks varies considerably from country to country as well as from region to region. This chapter aims to examine differentiated integration from a multi-level perspective, identifying and analysing contestation in integration goals between actors at different levels of governance. From a differentiated integration perspective, an analysis of the UK and Scottish government’s divergent attitudes towards Europe offers an opportunity to examine narratives of disintegration as well as narratives that aim to establish collaboration in new or existing networks. We use the case of fisheries policy to highlight that there are divergent narratives that are shaped by domestic political environments but also by functional imperatives. Brexit has brought into focus the political importance of fisheries and the multi-level tensions that exist within the UK in terms of the future relationship with the European Union. Overall, the chapter provides evidence of multi-level tensions in relation to differentiated integration.