Generally speaking, one can characterise the party system in Northern Ireland as a composite of two overlapping party systems. Nationalists choose between the Social Democratic and Labour Party (SDLP) and Sinn Féin, along with a cluster of smaller non-aligned parties such as the Alliance Party and the Northern Ireland Women’s Coalition. Unionists choose between the Ulster Unionist Party (UUP) and the Democratic Unionist Party (DUP), the above mentioned non-aligned parties and some smaller, often paramilitary-linked, unionist parties.
Sinn Féin is a radical socialist revolutionary party, theoretically committed to espousing an all-Ireland Socialist Republic, and linked with the Provisional Irish Republican Army. Traditionally the party of the urban Catholic working-class and a number of rural areas, since the IRA ceasefires of the mid-1990s it has expanded its base considerably, and has overtaken the long-dominant SDLP in terms of vote share. The experience of government has also blunted the edge of the party's revolutionary enthusiasms. Sinn Fein's MEPs sit in the European United Left - Nordic Green Left group in the European Parliament although are not full members of it.
The SDLP are a nominally social democratic party and a full member of the Party of European Socialists and Socialist International. However, as the Northern Irish party system is not based on socio-economic divisions, it inevitably attracts a wider spectrum of opinion and has a middle-class support base. The SDLP supports Irish reunification, but reject utterly the use of violence as a means to that end. The SDLP has lost considerable support in the past decade, and there seems to be a struggle within the party between those who wish to see it adopt a post-Nationalist agenda and those who wish to move onto more Nationalist ground to take on Sinn Féin.
Similarly, on the Unionist side of the political spectrum, the more radical DUP has overtaken the traditionally dominant Ulster Unionists in recent elections. The Ulster Unionists were historically a cross-class massenpartei who formed the government of Northern Ireland from its creation until 1972, although since the rise of the DUP in the 1970s their support has been more middle-class. Until 1972 the UUP’s members of the House of Commons took the Conservative Party whip, although for the past 32 years they have sat as a party in their own right. The UUP’s member of the European Parliament belongs to the European People's Party group.
The DUP are a more complex mixture than the other major parties – combining support from rural evangelicals and from urban, secular, working-class voters. The party is firmly to the right on issues such as abortion, capital punishment, European integration and equal opportunities, although the party seems to be moderating its stance on gay rights. Conversely, the DUP often support social programmes which benefit their working class or agricultural base, for example, free public transport for the elderly and European Union agricultural subsidies. The DUP have grown in recent years as they are the only major party to oppose the Good Friday Agreement. Their MEP sits as an Independent in the European Parliament, but is perceived to be close to the Independence & Democracy group.
The smaller Progressive Unionist Party and New Ulster Political Research Group are linked with the Ulster Volunteer Force and Ulster Defence Association respectively. The UK Unionist Party is essentially a one-man show led by Robert McCartney MLA for North Down.
Among the cross-community parties, the Alliance Party draws its support mainly from middle-class professionals in the suburbs of Belfast. It professes to be the only significant party which does not base its political stance around the constitutional question, and is a member of the European Liberal Democrat and Reform Party and Liberal International.
The future of the Northern Ireland Women's Coalition is in doubt after they lost both of their seats in the Northern Ireland Assembly. This feminist party drew support predominantly from middle-class professionals, and not exclusively from women, particularly among those working in the public or voluntary sectors.
Other parties who contest elections in Northern Ireland include the Green Party, the Workers Party and the Northern Ireland branch of the Conservative Party.
There are also two tiny parties seeking independence for Northern Ireland, although this is often perceived to be an ethnically Protestant or Unionist ideal with little real support.
Some commentators believe there are indications that the religious and ethnic basis of the party system may start to disintegrate. For example, in the 1998-2003 Assembly, there was a Catholic member of the Ulster Unionist Party. The SDLP have had a number of Protestant representatives in the past. However, these tend to be one-off events, which have occurred periodically throughout Northern Ireland’s history without setting a trend – cf. Sir Denis Henry in the early part of the 20th Century. In any event, social class is an important part of competition within the main ethnic political blocs, and class-based party structures in other established democracies have weakened since the end of the Cold War. Since the beginning of the peace process, the non-ethnic parties have declined, while the more radical Sinn Féin and DUP have prospered.
Optimists counter that, in the long-term, as the constitutional question may become less relevant due to the emergence of the European Union, and therefore a less sectarian political system may develop.
The dialect of English spoken in Northern Ireland shows heavy influence by that of Scotland, thereby giving it a distinct accent compared to other forms of Hiberno-English, along with the use of such Scots words as wee for 'little' and ay for 'yes'. Some jocularly call this version of Hiberno-English phonetically by the name Norn Iron. There are minute differences in pronunciation between Protestants and Catholics, the best known of which is the name of the letter h, which Protestants tend to pronounce as "aitch", as in British English, and Catholics tend to pronounce as "haitch", as in Hiberno-English. However, geography is a much more important determinant of dialect than ethnic background. English is by far the most widely spoken language in Northern Ireland.
Under the Good Friday Agreement, Irish and Scots have official recognition on a par with that of English. Traditionally, the use of the Irish language in Northern Ireland has met with the considerable suspicion of Unionists, who associated it with the overwhelmingly Catholic Republic of Ireland, and later with republicans.
Ulster Scots comprises varieties of the Scots language spoken in Northern Ireland. Many claim it has become a separate language, descended from Scots in Scotland, whereas others question whether Scots is a separate language from English at all, or simply a collection of local dialects of Scottish and Northern Ireland Hiberno-English.
Chinese and Urdu are also spoken by Northern Ireland's Chinese and Asian communities. Given the size of the Chinese community in Northern Ireland, Chinese is now the second most widely spoken language, according to the most recent census returns.