The pros­pect of the United King­dom leav­ing the Euro­pean Union (EU) in 2019 casts a sha­dow on the al­ready un­stable peace in Northern Ireland, the British ex­clave in the north­east of the island of Ireland. This report out­lines the app­roach, frame­work cond­itions and course of the Northern Irish peace process – as well as the signs of its im­pending col­lapse. It also out­lines the challenges that a “Brexit” poses for continued peace­ful relations in Northern Ireland.