There are up to 26,000 undocumented migrants in Ireland, and the vast majority of them are working here.
Research conducted by the Migrant Rights Centre shows that one in five have been living here for over a decade and the vast majority have been in Ireland for more than five years.
87% are working, and many have young children.
"The majority of people entered the country legally, and then have become undocumented," said Helen Lowry of the Migrant Rights Centre of Ireland.
"Some people are completely undetected, other people are known to the authorities - people are on tourist visa that have expired, student visas, [they] have fallen out of the employment permit system - so there's a variety of realities there"
"What we have found is that people are increasingly here long term, have put down roots, many are working, and are very much making a valuable contribution to Ireland."
The Department of Justice disputes the figures, saying it's not possible to be precise with such estimates, and has ruled out a regularisation procedure.
However, that's what the Migrant Rights Centre is calling for, asking the Government to afford migrants a similar amnesty to what has been proposed in the US.
"Last week, many Irish families and politicians expressed a lot of joy and a certain amount of relief at the prospect of regularisation in the United States, and we're saying it's time to look closer to home," Lowry said.