Younger people are significantly better educated than their older counterparts, according to new statistics released by the Central Statistics Office.
Almost 43% of people aged between 20 and 39 have a third level qualification, according to the 2011 Census, compared to just 13% of those aged 65 and over.
Educational attainment improved significantly in 20 years to 2011.
More women than men are third level graduates, 28% compared with 23%.
The number of those aged 15 and over with a third level qualification rose from 14% in 1991 to just 31% last year.
The percentage of people aged 15 and over with a third level qualification varied greatly by county.
The highest rate, two in five, was found in Dún Laoghaire-Rathdown and the lowest, 17%, was in Limerick city.
Almost nine out of ten(89%) 20-year-olds with parents educated to third level were still in full-time education.
That dropped to just over two thirds (68%) for those with parents educated to Leaving Cert level, and to 45% for those with parents who were not educated beyond lower secondary level.
Over 77,000 people spoke Irish on a daily basis outside of the education system in 2011.
More than half of the population of Galway county could speak Irish, the highest of any county.
The CSO found that daily Irish speakers were more highly educated than the population generally.
44% of them had a third level degree or higher, compared with 26% of the overall population.