Millions of historic personal records will be available online - free of charge - from today.
The records of births, marriages and deaths are being released by the General Register Office on irishgenealogy.ie.
The expanded online database will be launched in the National Library of Ireland later.
The launch will be attended by the Grandson of Antarctic explorer Tom Crean - whose records are included in the expansion.
Minister for Arts and Heritage, Heather Humphreys, and Minister for Social Protection, Leo Varadkar, will also attend.