© John Doyle & Eileen Connolly 2017. This chapter analyses the potential impact of Brexit on the Northern Ireland ‘peace process’, through a discussion of four interrelated issues-political divisions in Northern Ireland; the single market; the common travel area; and the Good Friday Agreement, all of which reflect the fundamental political divisions between Irish nationalists and those who believe that Northern Ireland should remain part of the UK. The chapter highlights two main threats to peace - the undermining of the Good Friday Agreement which is premised on membership of the EU and its institutional framework, and the crucial issue of where the inevitable hard border between the EU and the UK will be located. It argues that Brexit has the potential to destroy the peace process and suggests possible policy solutions to mitigate the impact of Brexit on Northern Ireland, while also assessing the political obstacles to the adoption of such flexible policy solutions.