The president Mary McAleese will lead the ceremonies today marking the 100th anniversary of the country's largest trade union, SIPTU.
Union president Jack O'Connor will deliver the key note address at the celebrations in Liberty Hall in Dublin.
While SIPTU was only set up in 1990 with the merger of the Irish Transport and General Workers Union and the Federated Workers Union of Ireland, the ITGWU had its beginnings 100 years ago when Jim Larkin began organising among the transport and dock workers in Dublin.
Over the years a number of other unions joined SIPTU which now has a membership of more than 200,000 members drawn from the services, industrial, professional and technical sectors.
Over the years the union has also moved from a position of frequent confrontation with employers to the centre of partnership which many have credited with creating the industrial peace needed for economic growth.