Northern Ireland has long been a contested territory. The 1998Belfast/Good FridayAgreement seemed to offer a resolution to the long-standing conflict. However, it has been reawakened by Brexit. Brexit presents a threat in Northern Ireland because it raises the divisive question of the United Kingdom¿s sovereignty over the region and the issue of the border. However, despite Nationalists¿¿a political identity group associated with the political ideology of Irish reunification¿initial opposition to Brexit, many in this group now view Brexit as a potential opportunity to achieve their political goal of Irish unity. The aim of the present research is to examine the combined influence of the Nationalist¿s identity and perceived Brexit threat on people¿s understanding of the proximity of this political goal.We specifically test whether Nationalists¿ strength of group identification, and the threat of Brexit, is linked to how likely people believe a United Ireland has become. In two studies, we found evidence for the prediction that strong ingroup identification is related to the perception that a United Ireland is more likely. In the second study, path analysis showed that this relationship is conditional on perceived threat. For Nationalists with stronger ingroup identification, the threat of Brexit is greater. Combined, these factors are linked to an increased sense that a United Ireland is likely. In the discussion, we consider the implications of our findings for polarization in this postagreement society.