Scottish Labour delegates have given their backing to a motion calling for a new federal UK.
The vote at the party's conference in Perth gives a green light to a People's Constitutional Convention.
Scottish Labour's deputy leader, Alex Rowley, said the move was a "historic" one.
The party said that the vote was the "culmination of months of work" by Scottish leader Kezia Dugdale and UK leader Jeremy Corbyn.
Ms Dugdale will give her main speech to the gathering on Saturday afternoon.
Mr Corbyn is expected to address the conference on Sunday.
Following the federal debate and vote, Mr Rowley said: "This is a historic vote as it commits Labour to Scotland remaining in a federal UK.
"Our call for a reformed UK isn't about constitutional tinkering - this is about meeting the demand for change.
"One message from the independence and EU referendums was that people wanted more control over their lives.
"That's why Labour's plan for a People's Constitutional Convention and a federal UK will transform where political and economic power will lie in our country."
What does Labour's federal plan mean?
By BBC Scotland's political editor Brian Taylor
What would be federated? The nations of the UK? But federating Scotland and England is like federating Connecticut and California. Scarcely comparable, it might be argued.
Might it then be, for England, a strengthened form of regional government? Perhaps. But it remains the case that there is relatively - I stress, relatively - little interest in affording priority to regionalism in England.
Plus enhancing English local government, without control of legislation or funding, would not be full devolution. It would not answer the West Lothian question for the Commons, posed by Tam Dalyell.
Ms Dugdale believed a more federal approach and a New Act of Union was needed.
In December last year, the MSP outlined her plan for a "federal solution" for the UK in a speech to the Institute for Public Policy Research in London.
She tasked former UK justice secretary Lord Falconer with exploring a federalist approach following the UK's vote to leave the EU.
Ahead of the conference starting, Ms Dugdale told the BBC that Mr Corbyn "fully supports a people's constitutional convention to examine issues of power across the UK".
Ms Dugdale added: "I have referred to it as an Act of Union and I understand Jeremy Corbyn might prefer to use other words because he has to examine the case for powers across the whole of the UK."
The Scottish Labour conference began hours after losing the Cumbrian constituency of Copeland in a by-election won by the Conservatives.
However, the party retained the Stoke on Trent Central seat in a second by-election that took place on Thursday.
Facebook interview with Kezia Dugdale
The BBC's Nick Eardley spoke to Scottish Labour leader Kezia Dugdale at her party's conference in Perth. Look back at what she had to say.