Taoiseach Enda Kenny has said that the Irish people are entitled to a full account of the causes of the banking collapse.
He was speaking in the Dáil as the motion setting up a formal inquiry was moved.
Mr Kenny said the most effective way to establish the full truth of the circumstances that brought the banking system to the edge of collapse was through an Oireachtas inquiry.
There had been a collapse of corporate governance and risk management and lessons had to be learnt so that that could never happen again, he said.
Tánaiste Eamon Gilmore said the Irish people needed to see and hear from those centrally involved in the crisis.
Some public servants, now retired, never had a chance to give their side of events and it was only fair that they be allowed to do so, he said.
There needed to be more than the dry narrative of a technical report to tell us how the decision to guarantee the banks was made, he added.
Fianna Fáil leader Micheál Martin said his party supported the inquiry but not attempts to politicise it.
He said he hoped it would mark an end to the Government's cynical and partisan approach to the crisis.
Mr Martin said the public had come to doubt whether politicians wanted to understand the crisis or to exploit it.
It would have been better if the Opposition had been consulted on who would chair it, he added.
The banking inquiry will have nine members and as expected will be chaired by Labour TD Ciarán Lynch.
The other members are Sinn Féin's Pearse Doherty, Fine Gael's Eoghan Murphy, Kieran O'Donnell and John Paul Phelan.
Michael McGrath will represent Fianna Fáil and independent TD Stephen Donnelly will also serve.
The Seanad will also nominate two members; one from Government and one from the Opposition.
The quorum for the committee will be five, including at least one member from the Seanad.
This means that at least five members will have to be present for the duration of all meetings of the committee.
The initial task of the joint committee will be to scope out its remit and undertake preparatory work and make a report to the Committee on Procedure and Privileges.
Independent TD Shane Ross this afternoon told the Dáil the inquiry was an attempt to put Fianna Fáil figures in the dock and to highlight the events surrounding the crisis as elections approach later this month.
Mr Donnelly said people were expecting the inquiry to be biased and political, but said there were two things that could be done to address this.
One more non-Government member could be added to the committee, which would take away the Government majority on any vote, he said.
Secondly, he said, the Taoiseach and the Tánaiste could publicly remove the whip.
Mr Doherty, Sinn Féin's finance spokesman, said it was important that the inquiry was dealt with robustly and that it was fair.
The inquiry could be no substitute for criminal investigations into wrongdoing, he said.
He said a banking inquiry conducted by parliament would always be limited, and the public will be frustrated by those limitations.