In the late 1980s, Reid facilitated a series of meetings between Gerry Adams and John Hume, in an effort to establish a 'Pan-Nationalist front' to enable a move toward renouncing violence in favour of negotiation. Reid then acted as their contact person with the Irish Government in Dublin from a 1987 meeting with Charles Haughey up to the signing of the Good Friday Agreement in 1998. In this role, which was not public knowledge at the time, he held meetings with various Taoisigh, and particularly with Martin Mansergh, advisor to various Fianna Fáil leaders.. After the eventual success of the peace negotiations, Gerry Adams said “there would not be a peace process at this time without diligent doggedness and his refusal to give up.” In 1988 in Belfast, Reid delivered the last rites to two British ArmyRoyal Signals corporals killed by the Provisional Irish Republican Army – an event known as the corporals killings – after they drove into the funeral cortège of IRA member Kevin Brady, who had been killed in the Milltown Cemetery attack. A photograph of his involvement in that incident became one of the starkest and most enduring images of the Troubles. Unknown until years later, Reid was carrying a letter from Sinn Féin President Gerry Adams to Social Democratic and Labour Party leader John Hume outlining Adams' suggestions for a political solution to the Troubles. Adams later told the BBC in 2019 that Reid also advised U.S Ambassador to Ireland Jean Kennedy Smith during the peace process, stating "He was talking to her on the side and she was talking to her brother Teddy." After he moved to Dublin, Reid was involved in peace efforts in the Basque Country. In January 2003, he was awarded the Sabino Arana 2002 "World Mirror" prize, by the Sabino Arana Foundation in Bilbao, in recognition of his efforts at promoting peace and reconciliation. Reid and a Methodist minister, the Rev. Harold Good, announced that the IRA had decommissioned their arms at a news conference in September 2005. Reid was involved in controversy in November 2005 when he made comments during a meeting in Fitzroy Presbyterian Church concerning the Unionist community in Northern Ireland. Reid said: "You don't want to hear the truth. The reality is that the nationalist community in Northern Ireland were treated almost like animals by the unionist community. They were not treated like human beings. They were treated like the Nazis treated the Jews". He later apologised, saying his remarks had been made in the heat of the moment. In an interview with CNN, Reid said that "The IRA were, if you like, a violent response to the suppression of human rights".
2008 - made an Honorary Graduate of the University of Ulster and made a Doctor of the University in their Summer Graduation ceremonies, in recognition of his contribution to the Northern Ireland peace process.
