Up to 150,000 young people are not registered to vote in next month's referendum.
There is just over one week to go until the deadline for signing up.
James Doorley from the National Youth Council of Ireland says it is important for young people to have a voice.
"We know from our work with young people that the vast majority want to vote but not all are aware they have to register," said Mr Doorley.
"This is particularly an issue among the more than 60,000 young people who turned 18 and became eligible to vote over in the last 12 months."
For those unsure whether they are registered or not, the NYCI advises that they check online at checktheregister.ie