The Army Council of the Provisional IRA has formally ordered an end to its armed campaign, effective from this afternoon.
It said in a statement it has also ordered all IRA units to dump their weapons, and all members have been "instructed to assist the development of purely political and democratic programmes through exclusively peaceful means".
The statement was read out by Séanna Walsh, one of the longest-serving republican prisoners and friend and cell-mate of hunger striker Bobby Sands.
The IRA leadership said it has authorised its representatives to engage immediately with the International Independent Commission on Decommisioning to verifiably put its arms beyond use "in a way which will further enhance public confidence and to conclude this as quickly as possible".
Two church representatives, one Catholic and one Protestant, have been invited to testify to the weapons decommissioning move.
IRA volunteers have also been ordered not to engage in "any other activities whatsover".
However, the statement said the IRA would not be disbanding despite demands by unionists that it do so.
"The Army Council took these decisions following an unprecedented internal discussion and consultation process with IRA units and Volunteers," the statement said.
"We appreciate the honest and forthright way in which the consultation process was carried out and the depth and content of the submissions.
"We are proud of the comradely way in which this truly historic discussion was conducted. The outcome of our consultations show very strong support among IRA Volunteers for the Sinn Féin peace strategy," the statement said.
The statement said organisation remained committed to a united Ireland and would be now following exclusively democratic means in order to do so. However, the Army Council said there was "widespread concern" about what it claimed was the "failure" of the Irish and British governments and unionists to fully engage in the peace process.
"This has created real difficulties. The overwhelming majority of people in Ireland fully support this process.
"They and friends of Irish unity throughout the world want to see the full implementation of the Good Friday Agreement."
It said it was aware there were concerns among nationalist communities about their future safety against attack. The IRA called for all sides to work towards ending sectarianism and ensuring there was no return to the "pogroms" of the late 60s and early 70s.
"There is now an unprecedented opportunity to utilise the considerable energy and goodwill which there is for the peace process. This comprehensive series of unparalleled initiatives is our contribution to this and to the continued endeavours to bring about independence and unity for the people of Ireland."
There was no mention of policing and no explicit mention of criminality in the statement.