Hundreds of young people from both sides of the border have been urged to remain on the island of Ireland to consolidate the peace process.
US Senator George Mitchell, who chaired the talks that led to the 1998 Good Friday Agreement, addressed them at Queen's University Belfast.
Around 600 young people attended the event called 'Passing on the Torch'.
They included young people from schools in Donegal and Dublin.
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Former taoiseach Bertie Ahern, a co-signatory of the Good Friday Agreement also attended, as did Minister for Further and Higher Education, Research Innovation and Science James Lawless.
They heard Senator Mitchell say there could be no complacency about what had been achieved in negotiations more than a quarter of a century ago.
He said the challenge for society was to keep its best and brightest minds at home.
"You, the young people of this island are needed here, in order to sustain this ongoing peace," said Senator Mitchell.
"Do not let your truths and dreams leave when there is so much to do at home."
He said the Northern Ireland peace process could continue to be a "lighthouse of peaceful engagement" to other troubled countries around the world especially at a time of disinformation and conflict.
Senator Mitchell said the key to securing peace was in the treatment of minorities and the embrace of difference.
"We cannot afford to isolate anyone, especially as history changes the nature of what is a 'majority' and a 'minority'," he said.
There was a small demonstration outside the event by protesters showing their support for Palestine.
