Sinn Féin is an all-island democratic socialist and Irish republican party. It is currently the largest political party in the Northern Ireland Assembly.

Sinn Féin literally translates into English as “We Ourselves”. It is the only major party that organises and contests elections in both Northern Ireland and the Republic of Ireland. The party currently serves as the official opposition in Dáil Éireann, the house of representatives of the Oireachtas (the Irish parliament).

In February 2022, Sinn Féin’s Michelle O’Neill assumed the office of first minister of Northern Ireland. O’Neill’s appointment was a landmark moment for Irish nationalism. She became the first nationalist politician to lead the Northern Ireland executive since the state’s establishment in 1921.

O’Neill’s elevation followed Sinn Féin’s emergence, for the first time, as the largest party in the Northern Ireland Assembly at the 2022 election.

The party also maintains its longstanding abstentionist policy, under which its elected MPs do not take up their seats in the House of Commons.

House of Commons representation: Sinn Féin won seven out of Northern Ireland’s 18 parliamentary constituencies in the 2024 UK general election. The party’s MPs do not take up their seats.

Northern Ireland Assembly: Sinn Féin won 27 out of 90 seats and 29.0% of the vote in the 2022 NI assembly election.

Local government representation: Sinn Féin won 144 councillors across Northern Ireland’s 11 councils in the May 2023 local government elections, making it the largest party at local government level.

Who is the Sinn Féin leader?

Sinn Féin has an all-island leadership structure. The party president (Uachtarán) is Mary Lou McDonald, who succeeded Gerry Adams in February 2018. The presidency is the party’s most senior post.

McDonald’s succession in 2018 represented a symbolic generational shift in the leadership of Sinn Féin. Adams was the longest serving president in the party’s history. The Good Friday Agreement was signed during his presidency.

​O’Neill is the party’s vice president (Leas-Uachtarán).

Mary Lou McDonald has been a Teachta Dála (TD) for the Dublin Central constituency since 2011, serving in the Irish parliament. Before becoming party president, she served as vice president from 2009 to 2018 and was previously a MEP from 2004 to 2009.

O’Neill is the party’s leader in Northern Ireland. She has represented Mid Ulster in the NI assembly since 2007 and previously served as deputy first minister and minister for health.

What does Sinn Féin stand for?

Sinn Féin’s core objective is the establishment of a single, united Irish republic, encompassing all 32 counties of the island. The party seeks to secure referendums on Irish unity in both Northern Ireland and the Republic of Ireland, as part of the process of achieving reunification.

Sinn Féin’s constitution recognises the “sovereign Irish Republic proclaimed in 1916” and states that the “sovereignty and unity of the Republic are inalienable and non-judicable”.

The constitution further defines the party’s objective as ending “British rule in Ireland”, achieving “territorial unification” and bringing the 1916 proclamation of a republic “into effective operation”.

Sinn Féin’s abstentionist policy is derived from its belief that the parliament at Westminster is illegitimate, and that its authority over Ireland rests on British sovereignty which the party does not recognise. Consequently, Sinn Féin MPs refuse to take their seats in the House of Commons, as doing so would require swearing an oath of allegiance to the British monarch, which the party regards as incompatible with its republican principles.

The party also exists to promote the “restoration of the Irish language and Irish culture and the widest knowledge of Ireland’s history; to make Irish citizens conscious and proud of their traditional and cultural heritage; and to educate the citizens of the Republic in their rights and responsibilities as citizens.”

In the foreword to the party’s manifesto for the 2024 general election, McDonald said Sinn Féin MPs would work “hard as part of a strong all-Ireland Sinn Féin team to deliver for all our people and communities.”

The manifesto added: “We want a stronger and fairer economy that delivers good jobs that pay well, offers workers secure conditions, and supports local business.”

Sinn Féin’s manifesto for the 2022 Northern Ireland Assembly election was centred on cost of living support. The party proposed a £230 payment to every household in Northern Ireland at a cost of £177 million. The manifesto also featured a pledge to put “an additional £1 billion into our health services over three years to tackle waiting lists”.

Sinn Féin argued that the then prime minister, Boris Johnson, had offered little support through the cost of living crisis, arguing that while people continue to “struggle, big corporations and energy companies’ profits soar.”

The party contended that Irish unification was “central to building a modern, inclusive, fair society and a country which can play its full part in the world.”

Sinn Féin party membership

An Irish Times report, published in September 2024, suggested that Sinn Féin has “more than 10,000 members” across the island of Ireland.

Sinn Féin structure and party organisation

Sinn Féin is a single, 32-county organisation. The party’s highest authority is the ard fheis (party conference), which elects the president and the ard chomhairle (national executive), the party’s main decision-making body.

The party is structured into local branches known as cumainn.

It has an active youth wing, known as Ógra Shinn Féin.

The party’s main headquarters is on Parnell Square in Dublin, with a major office in Belfast.

Its MEPs are part of The Left in the European Parliament.

Who votes for Sinn Féin? (Demographics of support)

The following data is drawn from the 2022 Northern Ireland Life and Times (NILT) survey conducted by ARK, regarding first preference votes in the 2022 assembly election.

Age: Sinn Féin won an estimated 26% of the vote among those aged 18-24 at the 2022 NI 2022 assembly election.

This result suggests Sinn Féin established a significant lead over rival parties in the 18-24 age bracket. The non-aligned Alliance Party placed second among those aged 18-24 on 17%.

Sinn Féin also won 23% of the vote among 25-34 year olds.

Conversely, Sinn Féin only secured 12% of the vote among those aged 65 and over. This data suggests support for the party was relatively stronger among younger voters.

Gender: Sinn Féin won 20% of the vote among women and 18% of the vote among men at the 2022 NI Assembly election, according to the NILT survey.

Religion: Sinn Féin’s voter base is almost entirely concentrated within the Catholic community. Sinn Féin won 47% of the vote among Catholics, making them the overwhelmingly most popular party within that community (leading Alliance at 22%).

By contrast, Sinn Féin secured only 1% of the vote among Protestants and 14% among those with no religion.

History of the Party

1905-1918

On 28 November 1905, Arthur Griffith presented his “Sinn Féin policy” at the first annual convention of the National Council. Griffith, a writer and journalist, articulated a political platform centred on establishing “a national legislature endowed with the moral authority of the Irish nation”.

Griffith had created the National Council in 1903 to campaign against King Edward VII’s visit to Ireland. The Sinn Féin (“We Ourselves”) policy, meanwhile, was heavily influenced by Griffith’s 1904 work, The Resurrection of Hungary: A Parallel for Ireland.

Griffith advocated a dual monarchy solution, modelled on the Austro-Hungarian Compromise of 1867, in which Ireland would be a separate kingdom alongside Great Britain. Griffith argued that Acts of Union of Great Britain and Ireland (1800) were, in fact, illegal. He believed that the Anglo-Irish dual monarchy and the Constitution of 1782, which provided Ireland with legislative independence, were still in effect.

Griffith, influenced by the tactics adopted by dissidents in Hungary, proposed a strategy of abstentionism and passive resistance. He argued that Irish nationalist MPs should withdraw from Westminster to form a national assembly in Dublin.

In The Resurrection of Hungary, Griffith argued: “The Hungarians resorted to a manly policy of passive resistance and non-recognition of Austria’s right to rule – the Irish resorted to parliamentarianism, implying recognition of an English right to rule this country.

“And one nation today is rich, powerful and able to defy her conqueror, while the other is poor, weak and more tightly held in the conqueror’s grasp.”

The party’s foundation represented a political challenge to the hegemonic Irish Parliamentary Party (IPP), which pursued home rule as a constitutional nationalist force.

Sinn Féin was initially unsuccessful in electoral terms, however. In the 1908 North Leitrim by-election, the Sinn Féin candidate, Charles Dolan, secured 27% of the vote; the IPP’s Francis Meehan won 72.8% of the vote and a majority of 1,946.

On Easter Monday, 24 April 1916, an armed insurrection against British rule began in Dublin.

The Easter Rising, marked by the proclamation of an Irish republic, was initially met with bemusement and even hostility from many Dubliners. However, the week of fierce fighting, the destruction of much of central Dublin by artillery fire, and the British government’s hardline response – including large-scale arrests, the killing of civilians and the execution of rebel leaders – radicalised public opinion.

485 people were killed over the six days of conflict, including 260 civilians, 126 members of the British armed forces, 82 rebels and 17 police. More than 2,600 were wounded, including at least 2,200 civilians and rebels.

Griffith did not take part in the rising. But the British press and political class labelled it the “Sinn Féin Rebellion”. (Nationalists seen as more radical than the IPP were generally referred to as “Sinn Féiners”.)

The IPP’s mode of constitutional nationalism did not survive the Easter Rising. Public opinion shifted decisively towards the mode of nationalism associated with Sinn Féin. In February 1917, Count George Noble Plunkett – father of the executed leader Joseph Plunkett – won the North Roscommon by-election as an independent “Sinn Féiner” nationalist.

In May, Sinn Féin’s Joseph McGuinness won the South Longford by-election with a majority over 37 of the IPP candidate. At the time, McGuinness was serving a prison sentence for his role in the Easter Rising; Sinn Féin’s campaign slogan was “Put him in to get him out”.

In July, Éamon de Valera, recently released from imprisonment for his role in the Easter Rising, won the Clare East by-election with 71.1% of the vote. Finally, in August 1917, Sinn Féin’s W. T. Cosgrave won the Kilkenny City by-election with 66.3% of the vote.

At the October 1917 Ard Fheis, a motion was agreed defining Sinn Féin’s goal as “securing the international recognition of Ireland as an independent Irish republic.”

Sinn Féin’s constitution also reflected initial tensions between republican and monarchist nationalists. The agreed motion added: “Having achieved that status the Irish people may by referendum freely choose their own form of government.”

The party’s new constitution continued: “Whereas no law made without the authority and consent of the Irish people is or ever can be binding on their conscience.

“Therefore in accordance with the resolution of Sinn Féin adopted in convention, 1905, a constituent assembly shall be convoked, comprising persons chosen by the Irish constituencies as the supreme national authority to speak and act in the name of the Irish people and to devise and formulate measures for the welfare of the whole people of Ireland.”

At the 1917 Ard Fheis, Griffith also stepped aside to allow de Valera to become president of the party. Sinn Féin was shifting steadily to unambiguous republicanism.

The Easter Rising, in reshaping the Irish political landscape, effectively created the conditions for Sinn Féin’s replacement of the IPP as the spokesperson for nationalism. At the 1918 general election, the party – founded just 13 years previously – won 73 out of 105 Irish seats. The IPP secured six seats – a net loss of 74.

Among the successful Sinn Féin candidates were Griffith, in East Cavan, and Constance Markievicz, who became the first woman elected to the House of Commons.

In line with the Sinn Féin policy, neither Griffith, Markievicz nor any successful Sinn Féin candidate took up their seats. Instead, the Sinn Féin representatives assembled at the Mansion House in Dublin on 21 January 1919 to form Dáil Éireann.

The first act of Dáil Éireann was to declare Irish independence.

The Sinn Féin representatives resolved: “Now, therefore, we, the elected representatives of the ancient Irish people in national parliament assembled, do, in the name of the Irish nation, ratify the establishment of the Irish Republic and pledge ourselves and our people to make this declaration effective by every means at our command.”

The revolutionary parliament also resolved that a state of war existed “between Ireland and England”. The Irish Volunteers, formed in 1913 to reinforce nationalist demands for home rule, were restyled as the Irish Republican Army (IRA).

1918-c.1950

The IRA waged a guerrilla campaign against the British Army in the Irish War of Independence (1919-1921).

On 7 January 1922, following nine days of debate, Dáil Éireann ratified the Anglo-Irish Treaty by 64 votes to 57. The treaty, signed in London the previous month, brought an end to the Irish War of Independence (1919-1921) and established the Irish Free State. But instead of a sovereign republic, the treaty provided for dominion status, which meant Ireland would remain in the British Empire. Members of the Dáil would be required to swear allegiance to “King George V, his heirs and successors”.

The treaty debate held from 19 December 1921 to 7 January 1922 exposed a profound schism within the republican movement. The pro-treaty faction, led by Michael Collins and Arthur Griffith, argued that the agreement was a “stepping stone” to full independence and the best deal achievable at that moment. Collins and Griffith were both signatories of the treaty.

De Valera declared his opposition to the treaty on the grounds it did “not reconcile Irish national aspirations with association with the British government”.

De Valera responded to the treaty’s ratification by resigning as president of the Dáil. He immediately stood for re-election but was rejected by 60 votes to 58. Griffith was proposed to take his place.

De Valera then led his supporters out of the chamber. Collins responded: “Deserters all! We will now call on the Irish people to rally to us. Deserters all!… Deserters all to the Irish nation in her hour of trial. We will stand by her.”

This schism paved the way for the Irish Civil War, which was fought from June 1922 to May 1923.

The civil war cost more than 1,000 lives, including that of Collins, who was killed in an ambush on 22 August 1922. In the end, the pro-treaty provisional government ultimately defeated the anti-treaty forces.

The Irish Free State was established on 6 December 1922. Northern Ireland had the option to opt in or out of the Free State. The unionist government, led by James Craig as prime minister, chose the latter option.

Pro-Treaty deputies of Dáil Éireann and other supporters of the settlement formed a new political party, Cumann na nGaedheal, on 27 April 1923 at a meeting in Dublin. A merger with two other organisations in 1933 led to the formation of Fine Gael.

De Valera later grew frustrated with Sinn Féin’s continued policy of abstentionism from Dáil Éireann. In March 1926, de Valera proposed that Sinn Féin abandon the policy of abstentionism and enter the Dáil if the oath of allegiance was removed. When his motion was defeated at the Sinn Féin Ard Fheis, de Valera resigned and founded a new party, Fianna Fáil, in 1926.

The party’s history of schisms left Sinn Féin as little more than a rump for much of the 1930s and 40s.

Sinn Féin found renewed purpose in the 1950s after its ties with the IRA, cut since the civil war, were restored. The party reemerged from the relative wilderness as the paramilitary’s political wing.

In December 1956, at the outset of the IRA Border Campaign, the Northern Ireland government passed the Special Powers Act to ban Sinn Féin. The party remained banned until 1974.

1970-1998

Sinn Féin split again in early 1970, after the party’s Ard Fheis rejected a motion to end its long-standing policy of abstentionism from Dáil Éireann and other legislative bodies. The party opposing abstentionism later became known as “Official Sinn Féin”, which embraced a Marxist political outlook.

This schism occurred amidst the rapidly deteriorating security situation in Northern Ireland.

On 14 August 1969, the British government deployed troops onto the streets of Northern Ireland, marking the beginning of the British Army’s longest continuous operation, Operation Banner. Initially, the nationalist/Catholic community welcomed the army’s deployment. The arriving forces were viewed as an impartial peacekeeping force, and even as protectors against the Royal Ulster Constabulary (RUC) and loyalist rioters.

But this warm welcome was short-lived. Nationalist hostility to the British army was fuelled by the Falls Curfew (1970), Operation Demetrius (the introduction of internment in 1971) and Bloody Sunday (1972).

The main opposition to the British military’s deployment came from the Provisional Irish Republican Army (PIRA), which answered calls for a “defenderist” group. The Official IRA leadership came under criticism from its traditional supporters for failing to defend Catholic areas.

This sentiment was captured by the famous slogan: “IRA – I Ran Away”.

The deployment of the British Army signalled the beginning of a larger role for the UK government in Northern Ireland, paving the way for the imposition of ‘direct rule’ in March 1972 and the suspension of the Stormont parliament.

The Official IRA changed its name to the Workers Party in 1982.

Provisional Sinn Féin, meanwhile, emerged as the political wing of the Provisional Irish Republican Army.

Provisional Sinn Féin (or simply Sinn Féin) began to more fully embrace electoral politics during the 1980s. The phrase “armalite and ballot box” came to symbolise Sinn Féin’s dual strategy of combining political participation with the ongoing armed struggle. It was coined by Sinn Féin organiser Danny Morrison at the party’s October 1981 annual conference.

“Who here really believes we can win the war through the ballot box?”, Morrison asked. “But will anyone here object if, with a ballot paper in this hand and an Armalite [rifle] in the other, we take power in Ireland?”

The death of independent republican MP Frank Maguire in 1981 presented an opportunity for Sinn Féin to step up its electoral strategy. The subsequent by-election became a focal point for the hunger strike in the Maze Prison, where republican prisoners were protesting for the restoration of political status.

Bobby Sands, the leader of the IRA prisoners in the Maze prison, was nominated as an ‘Anti H-Block/Armagh Political Prisoner’ candidate. The H-Block was the section of the Maze prison in Belfast reserved for republican and loyalist paramilitary prisoners. At the time of the by-election, Sands had served four years of a 14-year sentence for possessing firearms.

Sands, upon his selection as the ‘Anti H-Block’ candidate, was already more than a month into his fast. Other nationalist parties stood aside, producing a highly polarised contest between Sands and the former Ulster Unionist Party (UUP) leader, Harry West.

The by-election turned into a de facto referendum on the hunger strike itself. Sands won with 30,492 votes (51.2%) to West’s 29,046 (48.8%). Over 3,000 ballot papers were spoiled — an unusually high number. Voter turnout was 86.9%.

A contemporary New York Times report read: “[The result] cast into doubt the view often expressed by politicians in London that the IRA is supported only by a fringe of the Catholic voters.”

The result marked the first major electoral breakthrough for the republican movement since the beginning of the Troubles.

Owen Carron, who served as Sands’ election agent, responded: “The nationalist people have voted against Unionism and against the H-blocks. It is time Britain got out of Ireland and put an end to the torture of this country.”

Sands’ death triggered another by-election in Fermanagh and South Tyrone. Carron was selected as the republican candidate on an ‘Anti-H-Block Proxy Political Prisoner’ ticket. Had the Representation of the People Act 1981 not barred prisoners serving sentences of more than a year from standing for parliament, another hunger-striker could well have been nominated.

Sands was the first of 10 republican prisoners to die after hunger strikes. The campaign came to an end on 3 October 1981, with only minor concessions granted by the Conservative government.

However, the episode had a profound and lasting impact on the political character of Sinn Féin, accelerating its shift towards a more strategic engagement with electoral politics.

Sinn Féin’s Gerry Adams, who had spearheaded the party’s reforms, stood as a candidate in the 1983 general election. He won the seat of Belfast West, defeating the Social Democratic and Labour Party (SDLP) candidate with 16,379 votes (36.9%).

This electoral success sparked a strategic reassessment of Sinn Féin’s longstanding abstentionist policy. In November 1986, Sinn Féin voted to overturn the longstanding policy of abstaining from the Irish parliament.

Adams argued: “The only feasible way to break out from our isolation, to make political gains and win support for our policies is by approaching people at the level they understood.”

This decision triggered a more minor split than previous Sinn Féin schisms, precipitating the formation of Republican Sinn Féin.

1998-2024

On 10 April 1998, Good Friday, after marathon all-party talks in Belfast, a historic peace accord for Northern Ireland was finally reached. The Good Friday Agreement (GFA), also known as the Belfast Agreement, established a new political framework designed to end 30 years of violent conflict and create a lasting and inclusive settlement.

The deal, which had been brokered by the British and Irish governments and chaired by the US special envoy, senator George Mitchell, was the culmination of years of complex and often fraught negotiations.

Sinn Féin had begun discussions with the SDLP and the British government in the early 1990s regarding a political settlement.

The declaration of a ceasefire by the Provisional IRA in August 1994 led to the beginning of a sustained political dialogue.

The GFA’s central pillar was the creation of a new, devolved Northern Ireland Assembly and a power-sharing executive, inviting unionists and nationalists to govern together.

In Northern Ireland, the agreement was spearheaded by the Ulster Unionist Party leader, David Trimble, and the Social Democratic and Labour Party leader, John Hume. The deal was subsequently endorsed in referendums in both Northern Ireland and the Republic of Ireland. It was endorsed by 71% of the vote in Northern Ireland and 94% in the Republic.

In the first election to the Northern Ireland Assembly, Sinn Féin won 18 seats. It was the second largest nationalist party (behind the SDLP) and the fourth largest party overall.

The Northern Ireland Assembly was suspended on 14 October 2002, following allegations about an IRA spy-ring within Stormont. The assembly had been suspended on previous occasions because the unionist parties refused to participate without additional reassurances about the republicans’ renunciation of violence.

Sinn Féin supplanted the SDLP as the predominant representative of nationalism in Northern Ireland at the 2003 assembly election. Simultaneously, the DUP emerged as the largest unionist party.

On 26 March 2007, in a moment of immense historical significance, the leaders of the DUP and Sinn Féin, Ian Paisley and Gerry Adams respectively, sat alongside each other for the first time and publicly announced their agreement to form a power-sharing government in Northern Ireland.

The private negotiating session that preceded the announcement was the first time the two parties had ever held direct talks. A target date of 8 May was set for the restoration of devolved government – which had been suspended for five years. The agreement was the culmination of the process set out in the St Andrews Agreement of 2006 and came after Sinn Féin took the crucial step of formally endorsing the Police Service of Northern Ireland.

On 8 May 2007, Paisley was sworn in as first minister and Sinn Féin’s Martin McGuinness as deputy first minister, ushering in a new era of devolved government.

The Northern Ireland Assembly was suspended again from January 2017 to January 2020. This suspension occurred in the aftermath of the Renewable Heat Incentive scandal, and the resignation of McGuiness as deputy first minister. Sinn Féin subsequently withdrew from the assembly and without the formation of a new executive, decisions over Northern Ireland affairs reverted to Westminster. Following talks between the parties, the assembly resumed in January 2020.

In February 2022, the Democratic Unionist Party withdrew its first minister from the executive, collapsing the power-sharing institutions. This action was taken in protest against the post-Brexit trading arrangements known as the Northern Ireland Protocol, which the DUP argued undermined Northern Ireland’s place within the United Kingdom.

On 3 February 2024, devolved government in Northern Ireland was restored following a two-year political stalemate. The impasse finally broke in late January 2024 after the DUP’s party executive voted to accept a deal with the UK government.

The restoration of the power-sharing arrangements resulted in Michelle O’Neill’s appointment as first minister. O’Neill of Sinn Féin became the first nationalist to hold the post since the creation of Northern Ireland in 1921.

O’Neill’s appointment followed the 2022 Northern Ireland Assembly election, which returned Sinn Féin as the largest party. It marked the first time that an Irish nationalist party won the most seats in an assembly election. Sinn Féin’s victory meant the party had the right to nominate O’Neill as first minister under the power-sharing arrangements agreed in 1998.

In her first speech as first minister, O’Neill said her appointment would open “the door to a future – a shared future.”

She added: “We mark a moment of equality and a moment of progress, a new opportunity to work and to grow together, confident in the idea that, wherever we come from and whatever our aspirations, we can and must build our future together…

“As an Irish republican, I pledge cooperation and genuine honest effort with all those colleagues of the British and unionist tradition who cherish the Union. This is an assembly for all: Catholic, Protestant and dissenter.

“Despite our different outlooks and different views on the future constitutional position, the public rightly demand that we work and deliver together, and also that we build trust and confidence in our ability to collectively do that.

“That will require courage and ambition, not just from those of us who are elected but from the public. We should all invest in this. The more of us who do that, the better chance it has to succeed.”

She referred to the Good Friday Agreement as the culmination of a process of “political accommodation that provided a peaceful and democratic alternative to 30 years of conflict.”

Meanwhile, Sinn Féin has continued to grow south of the border. In the 2020 Irish general election, the party under Mary Lou McDonald’s leadership won 37 seats – an increase of 14 on the 2016 election. McDonald described the result as “something of a revolution in the ballot box”.

Fianna Fáil, the largest party, won 38 seats with 22.2% of the vote. Significantly, in terms of vote share, Sinn Féin emerged as the largest party on 24.5%. Fine Gael won 15 seats on 20.9% of the vote.

At the 2024 Irish general election, Sinn Féin won 39 seats on a smaller vote share (19.0%).