This chapter examines the potential impact of Brexit on the future of the Union, providing a snapshot of public opinion and attitudes as the full implications of the UK’s departure start to become clear. In the first section, an overview of devolution in the UK is provided. In the second section, data on public opinion are provided from Scotland, Wales and Northern Ireland, as well as consideration of attitudes to the Union in England and to Irish unification in Ireland. In the third section, the case of Northern Ireland is examined in more depth. In conclusion, it is argued that the future of the Union depends upon a combination of factors: the UK government’s policy towards Scotland, Wales and Northern Ireland; the economic impact of Brexit; demographic change in Northern Ireland; and attitudes in Ireland to unification.