50,000 people are set to attend the BT Young Scientist and Technology Exhibition, which will be officially opened by President Michael D Higgins in Dublin today.
A record number of entries were submitted for this year's competition, which once again takes place at the RDS.
Now in its 53rd year, the exhibition continues to grow.
Over the next four days 550 science projects from all over the country will be on display.
They were chosen from a record 2,091 individual and group entries, involving 4,591 students.
375 schools will be represented, up 2% on last year.
Just under two thirds (61%) of this year's entrants are female, which the organisers consider to be a positive sign that girls interest in science, technology, engineering and maths (STEM) is increasing.
The most popular category for entries was Social and Behavioural Sciences, which accounts for 41% of the projects.
The county with the largest number of entries is Cork, followed by Dublin and Limerick.
The main exhibition will be open to the public from Thursday until Saturday. The winners will be crowned on Friday evening at an awards ceremony.
Also running alongside the main event will be the RDS Primary Science Fair, which is now in its eighth year.
Beginning on Thursday, hundreds of fourth, fifth and sixth class pupils from all over the country will display their science, technology, engineering and maths projects in a non-competitive forum.
Other events taking place include The Ultimate Science Show, Discover the Cosmos 3D and another show by mentalist David Meade.
On Thursday, the former Manchester United and England footballer Rio Ferdinand and Graeme Hackland, the IT Director at Formula 1 team Williams are taking part in an event to encourage young people from disadvantage backgrounds to pursue a career in STEM.
World of Robots and TITAN the Robot will also be back again this year to entertain the visiting public.