President Michael D Higgins will call on people to reflect on Ireland's successes and failures as he marks the 100th anniversary of the first Dáil sitting.
TDs and senators will today take part in a joint sitting of the Oireachtas in the Mansion House, where their predecessors gathered on January 21, 1919.
The occasion will be led by President Higgins and is one of the main events listed during the 'decade of centenaries'.
He will encourage the people of Ireland "to celebrate the centenary of our democracy and to reflect on our collective past, our successes and our failures".
Áras an Uachtaráin said Mr Higgins had sought to lead the national debate on the appropriate forms to commemorate the pivotal moments from our past, calling for a "narrative hospitality" which requires an openness to different experiences, and different perspectives on the events of the past.
Taoiseach Leo Varadkar will address the historic gathering today, which is due to get under way at 4.15pm.