This book examines how Ireland’s relationship with the European Union was affected by a succession of crises: the financial crisis, the migration crisis and the Brexit crisis in both the Republic of Ireland and Northern Ireland. The various crises were not of equal significance in Ireland. The financial crisis was a huge issue for the Republic but less so for Northern Ireland; Brexit had a major impact in both polities; the migration crisis was less controversial; and the foreign policy challenges had a minimal impact. This opening chapter will provide a summary of the main features of each of the main crises to be considered, from both the EU and the Irish perspective.