This Occasional Paper addresses the independence referendum in Scotland which took place on 18 September 2014 and its aftermath, which together have created an extended and ongoing constitutional moment, the implications of which for the future of the United Kingdom remain uncertain. In the referendum 55% of Scots said No to the question: ‘Should Scotland be an Independent Country?’. It was a very dramatic event but it should also be seen as part of a long process in the gradual devolution of power in the UK, not only to Scotland but also to Wales and Northern Ireland, a process which continues to move ahead at speed. Although the referendum did not result in a vote for independence, it has sparked a further process of decentralisation. The Smith Commission, established in the days after the referendum,1 was a body given the task of drawing up further radical powers for the Scottish Parliament. This resulted in the Scotland Act 2016, which sets out a series of powers that could make Scotland one of the most autonomous sub-state territories in the world. In this chapter I discuss the institutional arrangements and political conditions that formed the background to the referendum, the referendum itself, and the aftermath in which we saw such a quick move towards further, radical constitutional change. Insofar as the referendum marks a constitutional moment it is a fluid one, with the question now being asked: is the United Kingdom edging in a federal direction?