The UK Government has unveiled plans for the biggest transfer of power from Westminster to Wales since the Welsh assembly was set up in 1999.
The Bill is expected to transform the ability of the Assembly to pass new laws, and will see significant changes to the electoral system.
The Government of Wales Bill will have to "rubber stamp" the legislation.
Secretary of State for Wales Peter Hain described the bill as a "red letter day for devolution".
The legislation will means the assembly will not have to compete with UK Government departments for a slot in the Queen's speech at Westminster and the decision-making process should be much quicker.
It also paves the way for full law-making powers to be transferred to Cardiff Bay, but only after a referendum.
Welsh Secretary Peter Hain said the bill would deliver "made in Wales decisions for the benefit of Wales".
He told BBC Radio Wales: "It will allow a more streamlined decision-making process instead of having to wait for Westminster to give space in the queue in the Queen's speech."
But Mr Hain said he thought it was unlikely there would be a referendum on full primary powers before 2010.
He added that he would not expect there to be a referendum until a "consensus" on the issue emerged.
'Rigging of electoral system'
"What I hope this will do is settle for a generation - if not more - the whole constitutional obsession we have in Wales about the powers and the status of the assembly.
"This will make for a more powerful assembly so we can get on with the job of delivering policies for the people of Wales," he added.
But the assembly leader of the Welsh Conservatives, Nick Bourne, said he expected the bill to be "a rigging of the electoral system to suit the Labour Party" which would not work.
"It's going to be a recipe for constitutional crisis between Westminster and the assembly with the assembly having to go to Westminster in a begging bowl fashion to ask for pieces of legislation, or powers to pass legislation," he said.
Plaid Cymru assembly leader Ieuan Wyn Jones told BBC Radio Wales he did not expect the bill to give Wales a full parliament.
Regional list system
"It's going to be a rather timid measure to give into Welsh Labour MPs who are more interested in keeping their jobs in Westminster than the needs of the interests of Wales," he said.
And leader of the Welsh Liberal Democrats in the assembly, Mike German, also called it a "timid" step.
He added: "Instead of creating a strong parliament for Wales with proper law-making powers they settle for something far less than we would want."
The bill will legally separate the roles of the assembly government from that of assembly members for the first time.
This means that in the same way as the UK government is separate from the House of Commons, the government of Wales will be separate from the assembly.
Some elements are likely to be prove more controversial than others like plans to prevent defeated candidates in assembly elections being elected under the regional list system - something which has drawn criticism from the Welsh Secretary.