Alliance Party of Northern Ireland

The Alliance Party of Northern Ireland (APNI), or simply Alliance, is a liberal and centrist political party in Northern Ireland. Following the 2022 Northern Ireland Assembly election, it was the third-largest party in the Northern Ireland Assembly, holding seventeen seats, and broke through by placing third in first preference votes in the 2019 European Parliament election and polling third-highest regionally at the 2019 UK general election. The party won one of the three Northern Ireland seats in the European Parliament, and one seat, North Down, in the House of Commons, the lower house of the Parliament of the United Kingdom.

Founded in 1970 from the New Ulster Movement, the Alliance Party originally represented moderate and non-sectarian unionism. However, over time, particularly in the 1990s, it moved towards neutrality on the Union, and came to represent wider liberal and non-sectarian concerns. It supports the Good Friday Agreement but maintains a desire for the reform of the political system towards a non-sectarian future and, in the Northern Ireland Assembly, it is designated as neither Unionist nor Irish nationalist, but "Other" or "United Community".

The Alliance Party won its first seat in the UK House of Commons in the 2010 general election, unseating the former East Belfast MP Peter Robinson, First Minister of Northern Ireland and leader of the Democratic Unionist Party (DUP). Naomi Long was the first MP from the Alliance Party since Stratton Mills, who joined the party from the Ulster Unionist Party (UUP) in 1973. However, the DUP regained the seat at the 2015 general election, following an electoral pact with the UUP. In the 2019 general election, Alliance regained its presence in the House of Commons when Stephen Farry won the North Down seat vacated by the independent unionist, Sylvia Hermon. Earlier that year, the party's leader, Naomi Long, won the party's first seat in the European Parliament in the last European election before Brexit. Under Long's leadership, the Alliance Party exceeded expectations in the 2022 Northern Ireland Assembly election and gained numerous seats in the Northern Ireland Assembly.

The Alliance Party is a member of the Liberal International and Alliance of Liberals and Democrats for Europe, and is aligned with the Liberal Democrats in Great Britain.