More Irish people are returning home than emigrating for the first time since 2009.
According to the CSO there are now nearly five million people "usually resident" in the State.
Over 90,000 people immigrated into Ireland in the first four months of the year - nearly one third of whom are returning Irish nationals.
Over 56,000 people left the country over the same time period - half of them Irish people.
CSO statistician James Hegarty said it is encouraging to see an increase in Irish people returning home.
from the says a third of them were returning Irish nationals.
"There is certainly a large number of people entering the country and now we can see that there is both Irish national and non-Irish nationals," he said.
"If that is an indicator that the country is going well, then that is certainly what we are seeing.
"On the other side then, there are less people leaving the country."
There are also encouraging figures in terms of employment - with the CSO finding that unemployment is continuing to fall and is now at 5.8%.
The figures reveal that employment rose by 3.4% in the first quarter of the year - with some 2.25 million people now in work.
However, the Irish National Organisation of the Unemployed has warned that people are still struggling to find 'decent' jobs.
"The headline figures are moving in the right direction but when you start to look underneath, you find that there are challenges there," she said.
"I think now some of the data is capturing the extent of those challenges.
"There are some people who are finding it a challenge to find work - or maybe to find decent work.
"Good work that would allow them to have a decent standard of living."
Overall, the figures suggest the economy is improving, however Austin Hughes chief economist with KBC Bank said there is still a long way to go.
"You have to remember employment is only about 1% than it was in 2007," he said.
"Whereas the population is about 10% higher; GDP is about 53% higher - so that is an entire fiction.
"The recovery is continuing, it is healthy, but it still has a way to go."