He was born Gerard Adams, Jr. in West Belfast into a strongly activist and nationalist Catholic family. He left St. Mary's Christian Brothers School early and became a bartender, but increasingly he became involved in the Republican movement, joining Sinn Féin and Na Fianna Éireann in 1964. He also probably joined the Irish Republican Army (an act he has always denied). Following the introduction of Internment in 1971 (the Special Powers Act) Adams was briefly interned in 1972 on the Maidstone, a British prison ship. He was considered important enough to be freed to take part in peace talks in 1972 but he was again arrested and interned from 1973 to 1977 at Long Kesh Internment Camp and briefly again in 1978.
In 1978 he became vice-president of Sinn Féin and in 1983 President, when a new Northern leadership deposed the southern leadership of Ruairi Ó Bradaigh. Part of the division was over Sinn Féin's decision to abandon its policy of 'abstentionism' (i.e., refusal to take its seats or to recognise the authority of the Westminster Parliament or Dáil Éireann, the parliament of the Republic of Ireland. Under Adams, the abstentionist policy towards the Dáil was revoked, leading to a walk out of O'Bradaigh and others and the setting up of a rival, small Sinn Féin under their leadership. However Sinn Féin continued its policy of abstentionism towards the Westminster parliament even after Adams won a seat in West Belfast. He lost his 'seat' in 1992 but regained it at the next election in 1997. He worked hard to move the republican organizations from "Armalite to ballot box". On March 14, 1984 he was seriously wounded in a Loyalist assassination attempt.
He was in talks with John Hume of the SDLP from 1988. In September 1993, Adams and Hume played a key role in reviving the Irish Peace Initiative. This led to major developments in the peace process including the Downing Street Declaration and the Joint Framework Document.
The successes of Sinn Fein led to the IRA's cease-fire in August 1994. That peace process later collapsed.