Having been issues which stimulated little discussion beyond Northern Ireland before the Brexit referendum, the 'Irish issue' dominated and complicated the subsequent EU-UK withdrawal negotiations. The 'taking back control' narrative bears the hallmarks of Prime Minister Boris Johnson's notion of a 'recaptured sovereignty'. This conception of sovereignty, however, clashes with the post-sovereign character and content of the 1998 Belfast/Good Friday Agreement. The institutions created by the Agreement move beyond the old frameworks for political order by creating a series of interlocking territorial, cross-territorial, and cross-national institutions based on shared sovereignty. This prompts critical questions about the resilience and sustainability of the Agreement against the backdrop of a shift in sovereignty which appears incompatible with the key tenets of Northern Ireland's peace agreement. This article examines how Northern Ireland's approach to and experience of the EU referendum differed from the rest of the UK. It queries how the referendum result, subsequent political and electoral developments, and difficulties in agreeing a withdrawal formula and future UK-EU relationship, expose the gap between the UK's commitments to a post-sovereign arrangement for Northern Ireland and the preference for a return to an older conception of sovereignty as implied by the Brexit vote.Unlike other parts of the UK, Northern Ireland's historic experience has been marked by serious and violent conflict. The movement from conflict to peace over a protracted period of time culminated in the signing of the Belfast/Good Friday Agreement in 1998. The evolving process of peace consolidation which followed was interrupted by the June 2016 referendum on the UK's membership of the European Union (EU). In Northern Ireland, a majority voted in favour of Remain. The referendum campaign, however, was different in tone and content to the rest of the UK (see Murphy 2016). It focused less on migration and 'taking back control', and more on issues, such as the future status of the border between Northern Ireland and the Republic of Ireland, the implications of a Leave vote for the (fragile) peace process and the impact on trade and policies. Having been an issue which stimulated little discussion beyond Northern Ireland before the referendum, issues pertaining to Northern Ireland and the Irish border came to dominate and complicate the subsequent EU-UK withdrawal negotiations. The 'taking back control' narrative which so animated Britain, and particularly England's, referendum narrative and the subsequent UK-EU negotiations bears the hallmarks of Prime Minister Boris Johnson's (2020) notion of a 'recaptured sovereignty'. This conception of sovereignty, however, clashes with the post-sovereign character and content of the 1998 Belfast/Good Friday Agreement. The principles and institutions established by the Agreement move beyond the old frameworks for political order by creating a series of novel and interlocking territorial, cross-territor...