A challenge is being put to schools around Ireland - to speak Irish for 24 hours.
Conradh na Gaeilge says more than 32,000 people from 340 schools in every county are to take part on Tuesday.
Both English and Irish medium primary and secondary schools, within the Gaeltacht and all over the country, will participate.
A number of groups will also take up the challenge abroad.
Gaeilge24 is encouraging young people to push themselves to speak only Irish for 24 hours, in all aspects of their lives.
Students will be asked to speak Irish only - not just in school and with teachers - but at home, in shops, with friends and at after-school activities such as their sports clubs.
Seo chughainn Gaeilge 24! We're taking on the challenge to speak Irish for a day!
Ní baol dúinn!! #Gaeilge24 @CnaG pic.twitter.com/YiiBmVGUQX— Scoil Bhailenóra (@SBNORA) November 9, 2018
Certificate for every student
Dr Niall Comer is president of Conradh na Gaeilge.
He says: "Gaeilge24 encourages a positive mindset towards the language in young people, by making it fun and relevant.
"It gives them an opportunity to see the ways in which they can incorporate Irish into their everyday lives, and leaves them with a positive experience of using the language".
There will be a certificate available for every student who takes part.
This year, Gaeilge24 is being organised as one of the main school year events for Bliain na Gaeilge.
Every registered group across the 32 counties will undertake a challenge at 1.25pm to celebrate 125 years since the beginning of the revival of the Irish language.
According to feedback collected last year, 94.1% of teachers said their school would want to take part in Gaeilge 24 again.
Tá an scoil ar fad ag tnúth go mór leis #Gaeilge24 Dé Céadaoin @accsirl pic.twitter.com/OuPS4bUsim
— Portmarnock CS (@PortmarnockCS) November 11, 2018
Cillian Ó Braonáin, a teacher who organised Gaeilge24 in Coachford College, Cork says: "Gaeilge24 is a great cause for excitement in our school.
"We hold Seachtain na Gaeilge for the whole week, with Gaeilge24 at the heart of it.
"It is a great incentive for the students, who get great enjoyment out of it.
"There is always a demand for the wristbands and t-shirts, and the number of students wanting to take part increases every year."
