The latest figures from the CSO reveal almost 270,000 men and 190,000 women aged 18 and over remain in the family home.
"The new figures highlight the lack of affordability in the housing and rental sector," says Labour Housing spokesperson, Jan O’Sullivan TD.
She says the CSO data released shows how "urgent" it is for the Department of Housing to act on the basis of accurate data; not just the number of adults living with their parents but also the "hidden homeless" who are couch surfing.
“We need to know the size of the problem and to ensure that Housing remains on top of the priority agenda for capital spending,” she says.
“That so many adults are still living at home with their parents highlights the extent to which young people in particular are finding it simply unaffordable to rent, or later buy a house.
“It is becoming more common for young couples and families to move in with their parents when they are trying to save for a deposit for a house.
“While it is great that so many people have the option to remain or indeed move back home, these figures once again highlight the extent of the problem in the housing sector here."
She added: “And for those that don’t have the option to live with family, many people and families are ending up on the streets.
“Government has to address the crucial supply issue and make use of the thousands of vacant properties around the country to begin addressing this crisis.
“But action is also needed in relation to affordable housing, and a glaring omission in Government strategy to date is the complete lack of will to introduce a national Affordable Housing Scheme."
The 2016 Census figures released by the CSO yesterday "make stark reading", according Labour spokesperson on urban regeneration, Joe Costello.
"The quality of life for young adult working males, in particular, has deteriorated sharply in recent years," he says. "The shortage of affordable housing and the prevalence of low paid employment is playing havoc with young people’s lives.
"And what is the Government’s response? The other night on the Vincent Browne Program on TV3, the new Taoiseach, Leo Varadkar, admitted that his Government would meet none of its targets on housing and homelessness during its lifetime.
"Thus, a generation of Irish youth which get up early in the morning and goes to work each day will continue to face the prospect of living with their parents and never having a place of their own.
"His further statement on the same program is even more worrying. He declared that it is belief that those working on the minimum wage which is only €9.25 per hour constitute ‘middle Ireland.’
"This is indeed cold comfort for young working adults. It demonstrates that the Taoiseach is totally ignorant or totally uncaring of what people in poorly-paid employment, compelled to live their parents experience.Under the new Taoiseach Fine Gael has lurched massively to the right."