The 43rd session of the European Youth Parliament (EYP) was officially opened by the President, Mrs McAleese, in Dublin Castle this morning.
Addressing the gathering - which gives young Europeans an opportunity to debate issues, form resolutions and vote on them - Mrs McAleese said she was "very encouraged" to see so many young people in such a "unique" setting.
"If you build up Europe, you build up the world. You are the dreamers and doers," she stated.
"Don't underestimate what you are doing here. I hope you'll realise your burning ambition to make the very best Europe possible," Mrs McAleese added.
Over 150 delegates from 20 different countries are attending the sitting, which will run until this Friday. It was last staged in Ireland in 1995.
The EYP was founded in France in 1987, with the aim of providing an educational forum for Europeans aged 18 to 22. It sits in three nine-day sessions a year, each held in a different city. Representatives from all of the EU member states attend the parliament, as well as those from countries such as Lithuania, Ukraine and Turkey.
During the sittings, the members debate on selected themes, with a view to reaching a consensus and preparing a "white paper" on this. This work will be undertaken at DIT, Aungier Street, over the coming two days.
The resolution is then voted on during a two-day General Assembly, which will sit at Dublin Castle. Adopted resolutions are presented to the European Parliament.