The Nationalist Party existed under various froms from 1874 to 1973. It was founded under Isaac Butt as the Home Rule League. After the death of Butt the party soon divided into radicals led by Charles Stewart Parnell and Whiggish members under William Shaw . Shaw became leader for a year 1879-1880, but was defeated by Parnell the next year. The Whiggish members all lost their seats in 1885. The party was reformed by Parnell as the Irish Parliamentary Party in 1882.

The party split in 1891 over the leadership of Parnell. He had been named by party member William O'Shea as the cause for his divorce with his wife Katherine. When the Liberal Party leader William Ewart Gladstone stated that he couldn't work with the party under the circumstances the majority of the party called for his resignation early in 1891. He died that year from pneumonia after fighting three tough bye-elections, all of which he lost. This further split the party, with the Parnellite wing, led by John Redmond, blaming the Anti-Parnellites for his death.

The party remained split until 1900, when Redmond became leader, with John Dillon, then leader of the Anti-Parnellites, as his deputy. Throughout the period 1900-1910 Tim Healy, D.D. Sheehan and William O'Brien lead breakaway factions, but never achieved more than eight seats, and they usually sat and voted with the rest of the party.

It seemed that Irish Nationalists might achieve their aim of Home Rule in 1910 when the Liberal government of Herbert Henry Asquith depended on them to stay in power. In exchange for voting for the Parliament Act, they were promised a Home Rule Bill, which they got in 1912. Under the new provisions the House of Lords could only delay bills for two years, so they expected to have it in 1914. However, militant unionist resistance in Ulster had risen in those years largely due to a lack of consideration for protestant interests and an unwillingness on the part of southern Nationalists to compromise, so that with the outbreak of the First World War, a provision was added to the final Third Home Rule Act 1914 that the bill wouldn't be enacted until after the war, and until a temporary partition provision was made for Nothern Ireland.

However, by the time the war had ended the party had lost support. With the Easter Rising of 1916, its failure to enact Home Rule immediately and the fear that conscription could be extended to Ireland, it lost support to the more radical Sinn Féin. In the election of 1918 its seats fell from 73 to 6, Sinn Fein claiming a largely unopposed clear run.

It disappeared after the Irish War of Independence, theGovernment of Ireland Act 1920, subsequent Anglo-Irish Treaty and Irish Civil War in what was to become the partitioned Irish Free State, with some of its members joining the Centre Party, founded by John Dillon's son, James, which amalgamtated with Cumann na nGaedheal to form Fine Gael in 1933.

It continued in the north, but developed a reputation for being heavily disorganised and being little more than a collection of elected members with their own local machines. Many calls were made for the party to develop an overall organisation but it fell apart in the late 1960s, with many of its members later joining the Social Democratic and Labour Party, founded in 1970. Its last electoral contest was the 1973 for the Assembly created as part of the Sunningdale Agreement.

Leaders

• Isaac Butt 1874-1879
• William Shaw 1879-1880
• Charles Stewart Parnell 1880-1891
• Justin McCarthy 1891-1892
• John Dillon 1892-1900
• John Redmond 1900-1918
• Joe Devlin 1918-1934
• T.J. Campbell 1934-1946
• James McSparran 1946-1953
• Eddie McAteer 1953-1959
• Cahir Healy 1959-1965