The Irish presidency of the European Union was a "job well done", the Taoiseach told the Dáil on the last day of Ireland's six-month term today.
The Taoiseach, who relinquishes his position President of the European Council tomorrow, said the successful outcome of negotiations on the EU constitution "marked a milestone in the development of the European Union".
"Each participant could justifiably claim the European Constitution as their own," he said.
Describing the "complex and critical negotiations" as a "classic European Union exercise", Mr Ahern said: "Our collective success was particularly noteworthy as this was the first major test of our new enlarged Union of twenty-five and more".
The constitution had proved to be a "win-win solution for all the member states and for the people of Europe," he added.
Mr Ahern has been widely complemented for his handling of the negotiations, particularly after agreement looked bleak following a breakdown in discussions during Italy's presidency.
The Taoiseach was uncharacteristically downbeat about the prospect of agreement shortly after he succeeded Italian Prime Minister Silvio Berlusconi in January. But by March, EU leaders resolved to push for a deal, giving Mr Ahern the opportunity to display his renowned conciliation and consensus-building skills, through a series of bilateral meetings with every EU head of Government.
Mr Ahern was able to cap his presidency with agreement on who should be appointed to the new role of European Commission President yesterday when he confirmed unanimous backing for the Portuguese Prime Minister Mr Jose Manuel Barroso.
Opposition parties took the opportunity to compliment Mr Ahern and the Government on their handling of the presidency in the Dáil today.
"The Taoiseach's rare achievement is a testament to his negotiation skills which, we are told, are legendary," Fine Gael leader Mr Enda Kenny said.
He also paid tribute to the Ireland's public servants who were "the unsung heroes of this complex Treaty negotiation, and indeed of the efficient management of this latest Irish Presidency".
"We owe them a debt of gratitude", Mr Kenny said.
Labour Party leader, Mr Pat Rabbitte said getting agreement on the treaty and the presidency of the European Commission "in the midst of a remarkable degree of rancour between various heads of government are noteworthy and are deserving of unbegrudging congratulations".
Mr Rabbitte also praised the Minister for Foreign Affairs, Mr Cowen, and the diplomatic corps, which he said was "among the very best".