Over 1,000 volunteers from the Society of St Vincent de Paul have gathered in Dublin to mark the bicentenary of the birth of its founder Frederic Ozanam.
President Michael D Higgins opened the event and described the charity as a "jewel".
Mr Higgins thanked its members for freely giving up their time to visit the poor.
There are now 10,500 members of the SVP in Ireland.
It received over 100,000 calls for assistance last year.
It is now helping more than double the number of people it assisted in 2009.
The President of the Saint Vincent de Paul Geoff Maher said that many people who used to be donors have become recipients in recent years.
The Minister for Social Protection Joan Burton said the new insolvency regime will help those who use the charity's services.