A major report into the future of Welsh devolution has recommended more powers for the assembly, 20 more assembly members and a change in the electoral system.
The Richard report calls for the Welsh assembly to have primary law-making powers and "desirable, though not essential" to have the power to vary tax.
First Minister Rhodri Morgan said it was a "red letter day for Wales" but there should be no "rush to judgment" on its findings.
The report was welcomed by the Welsh Liberal Democrats, Plaid Cymru said it did not go far enough, and the Conservatives called for a referendum.
The commission, chaired by Labour peer Lord Ivor Richard, also says the current system of electing 40 AMs for constituencies and an extra 20 on a list system cannot be sustained if the number is raised to 80.
It calls for a switch to the single transferable vote system, under which electors choose candidates in order of preference.
Other recommendations are for a separation of the legislature - the rest of the assembly - from the executive or the assembly government.
It also says these changes "should be in place by 2011 or sooner if practicable".
Primary law-making powers by 2011 or sooner
Desirable, but not essential, to have tax powers
Rise from 60 to 80 AMs
Change electoral system to "single transferable vote"
Change structure, with separate executive and legislature
The report makes no recommendation on whether there should be a new referendum.
Lord Richard said he thought the arguments were "finely balanced" but a little "rarefied" at this stage.
He added, to laughter: "This is, I'm relieved to tell you, not a matter for us".
But although the ten commission members agreed the report unanimously, one, former Merthyr Labour MP Ted Rowlands, said he believed there should be a referendum before change.
Mr Rowland added a letter to the end of the report which said the evidence of devolution so far did not justify a change without another vote by the people of Wales.
Lord Richard said the present arrangements for the assembly "have been a success in many ways".
But he added: "We unanimously concluded that the assembly needs more powers in order to address Wales' needs and priorities most effectively and to be directly accountable to the people of Wales."
On the issue of overall change he said: "I feel the assembly is very rapidly outgrowing the existing structure."
The report estimates that the cost of expanding the assembly would be about £10m a year.
How single transferable vote works
Voters face a list of candidates in each constituency
They vote for them by preference, putting 1 for their favourite, and so on
Votes for first-choice candidates are transferred if they are elected or have too few votes to be elected
Votes are transferred to second-choice candidates, and the process is repeated
Result is constituencies have several elected members
The first minister told AMs later that they could debate the report on 28 April and again in the autumn, but warned: "The fate of the Richard report does not lie simply in the hands of the assembly."
Mr Morgan said change would only come through action at Westminster.
He said: "Careful, collaborative and co-operative discussions will be needed with Westminster colleagues of all political persuasions if we are to build on the excellent start this report has provided in building a consensus for change."
In a statement, Plaid Cymru said Wales has been governed for too long " by
parties whose first priority is London", and said the Richard report provided a chance to change that.
They welcomed the move towards primary law-making powers, but said the Richard Commission had "missed an opportunity to be even more radical in
Mike German, Welsh Liberal Democrat Assembly leader, welcomed the "clear vision" of Lord Richard's report.
"Two things are clear from the conclusions of the commission: independence is not an option and we cannot stay as we are," he said.
Nick Bourne, leader of the Welsh Conservatives in the assembly, who led the anti-devolution Just Say No group during the 1997 devolution campaign, said they were still opposed to giving the assembly law-making or tax-raising powers.
"Labour must not be allowed to sneak major changes to the way Wales is governed in through the back door."
"Any moves towards giving the institution legislative powers must be endorsed by the Welsh public," said Mr Bourne.