The agreement was reached between the British and Irish governments as well as eight northern Ireland political parties or groups. Three were representative of unionism: the Ulster Unionist Party, which had led unionism in Ulster since the early 20th century, and two small parties linked to loyalist paramilitaries, the Progressive Unionist Party (linked to the Ulster Volunteer Force (UVF) and the Ulster Democratic Party (the political wing of the Ulster Defence Association (UDA). Two of them have been widely described as nationalists: the Social Democratic and Labour Party and Sinn Féin, the Republican party affiliated with the Provisional Republican Army.   Apart from these rival traditions, there were two other assemblies, the Inter-Community Alliance Party and the Northern Ireland Women`s Coalition. There was also the Labour coalition. U.S. Senator George J. Mitchell was sent by U.S. President Bill Clinton to chair the talks between parties and groups.
 In 2004, negotiations were held between the two DUP and Sinn Féin governments for an agreement to restore the institutions. The talks failed, but a document published by governments detailing the changes to the Belfast agreement was known as the “comprehensive agreement.” However, on 26 September 2005, it was announced that the Provisional Republican Army of Ireland had completely closed its arsenal of weapons and had “taken it out of service”. Nevertheless, many trade unionists, especially the DUP, remained skeptical. Among the loyalist paramilitaries, only the Loyalist Volunteer Force (LVF) had decommissioned all weapons.  Further negotiations took place in October 2006 and resulted in the St Andrews Agreement. The result of these referendums was a large majority in both parts of Ireland in favour of the agreement. In the Republic, 56% of the electorate voted, 94% of the vote voted in favour of the revision of the Constitution. The turnout was 81% in Northern Ireland, with 71% of the vote for the agreement.
These themes – parades, flags and the legacy of the past – were negotiated in 2013 under the chairmanship of Richard N. Haass, president of the Council on Foreign Relations, and Meghan L. O`Sullivan, a professor at Harvard Kennedy School and now on the CFR board. The talks involving the five main political parties were not agreed upon, although many of these proposals – including the creation of a historic investigation unit to investigate unsolved deaths during the conflict and a commission to help victims obtain information about the deaths of their loved ones – were a large part of the Stormont House agreement reached in 2014.