The coalition deal between Labour and Plaid Cymru has been formally signed on the 10th anniversary of the vote which created the Welsh assembly.
Shake on it: Rhodri Morgan and Ieuan Wyn Jones seal the deal
Labour First Minister Rhodri Morgan and his deputy, Plaid Cymru leader Ieuan Wyn Jones, signed the One Wales document in the Senedd in Cardiff Bay.
The deal was sealed following wrangling after May's assembly election.
Mr Morgan said rejecting devolution in 1997 would have been "the greatest missed opportunity in Welsh history".
He said over the last decade Wales had grown up as a nation, and learnt to accept responsibility for its own political, economic, cultural and social development.
Mr Jones said the signing of the document was among many "firsts" after the inaugural meeting on Monday of the assembly government coalition cabinet, in which Plaid holds three posts.
Mr Jones said both Labour and Plaid were looking forward to working together, and that there was a clear recognition that the work to put their election promises into practice started now.
He identified a number of key priorities - health, structural funds, affordable housing, climate change, improving transport and the creation of a new constitutional convention.
There was no statutory obligation on the parties to sign the document, but they decided to do it to mark the 10th anniversary of the 1997 devolution referendum.
Earlier in the summer, the party leaders shook hands on the deal just before Mr Morgan was taken ill with heart problems.
They met again as Mr Morgan recovered, and the coalition cabinet was finally agreed, 11 weeks after the assembly election.
Mr Morgan told the Devolution Decade conference at Cardiff's Wales Millennium Centre on Monday that devolution had given Wales the confidence to "stop blaming others for what they've done to Wales as the source of all our problems".
He said: "If the referendum result had gone the other way, Wales would still be rueing the day as the greatest missed opportunity in Welsh history.
"We have shaken off that essentially colonial complex that others have done us down, are doing us down and will always do us down and that there is nothing we can do about it except whinge."
Mr Jones has used the 10th anniversary of the devolution vote to call for Wales to be given "the parliament it deserves".
In a statement issued jointly with the party's honorary president, Dafydd Wigley, Mr Jones said: "Plaid has ensured that this is on the political agenda with a One Wales government commitment to a referendum on further powers.
"A legislative parliament will enable us to carry on making a difference and to make more of a difference."
Mr Wigley called on those who had "dragged their heels" over devolution to "recognise that further moves are inevitable".
He said Plaid recognised that it had to work with "the more progressive elements in the other parties".
He said: "It is time for everyone to embrace what is happening. Even those Labour politicians who have chosen to make their careers in London.
"People are seeing that only policies made in Wales will truly safeguard the interests of Wales."
A video booth has been set up at the Senedd to encourage the public to give their view on devolution and what they would like to see in the future. The videos will then be played at the Senedd for other visitors to see.