A report on the second Lisbon Treaty has been published suggesting the reasons that people voted for and against the treaty.
Irish people voted by a margin of two to one in favour of ratifying the Lisbon Treaty in October last year.
The 58% voter turnout was the highest in a European referendum since the original vote on joining the then EEC in 1972.
Ireland had rejected the Treaty in the first referendum in 2008.
Minister for Foreign Affairs Micheál Martin said: 'This represented a significant reversal of the result of the first referendum in June 2008.
'The findings suggest that the reasons underlying the different outcomes were complex and should not be oversimplified.
'What is clear, however, is the belief of most Irish people that the European Union is good for Ireland and that Irish economic wellbeing is linked to our membership of the union.'