Sir Menzies Campbell has used his first major conference speech as Lib Dem leader to say the party must show it is a serious prospect for government.
Unlike Labour and the Tories, the Lib Dems are "a party of substance, not of spin", he told delegates in Brighton.
"My objective is nothing less than to complete the transformation of the Lib Dems from a party of opposition into a party of government," he said.
Sir Menzies raised his arms aloft as he was greeted with two standing ovations.
Two days after ex-leader Charles Kennedy refused to perform a public handshake on the conference stage, Sir Menzies failed to make any mention of his predecessor and his turbulent resignation earlier this year.
Instead, Sir Menzies said the party must go forward showing it was both responsible and radical.
Gains in next year's elections could make Lib Dem Nicol Stephen Scotland's first minister, he predicted and the party's ambition must not end there.
"I have had three great opportunities in my life: in sport, in the law, and in politics," he said.
"And now I have been given one more: the opportunity to lead our party from opposition towards government."
His vision of the future was "free, fair and green".
Sir Menzies pointed to his victory in the crunch vote over his tax proposals this week.
The Lib Dems could now say exactly what they would do on tax - cutting income tax and using higher taxes on gas-guzzling cars and aviation to pay for it, he said.
The Conservatives say the plans will hit the pensions of middle earners.
The Lib Dems are playing up Sir Menzies' background
But Sir Menzies argued: "We will reward ambition and aspiration - not penalise effort."
The "very wealthy" would lose generous pension tax subsidies and tax breaks on capital gains would be removed.
The Lib Dem leader attacked Labour for failing to tackle the gap between rich and poor.
And there had been little improvement in public services, with NHS wards closing and doctors in despair.
And he accused ministers of putting civil liberties under threat and promised to fight any new attempts to allow terrorism suspects to be held for up to 90 days without trial.
"Terrorism thrives where civil liberties are denied," he said.
Sir Menzies also launched a broadside at Labour's foreign policy, saying Britain's reputation had been tarnished by a foreign policy which was "neither ethical nor effective".
He paid tribute to British troops who have died in action but argued that Iraq was approaching a civil war and Guantanamo Bay stood as an "affront to justice".
"Security is not being gained, it is being lost," he said.
"Terrorism is not being defeated, it is being invigorated. Freedom is not being spread, it is being undermined."
There was a dig too at the favourite to succeed Tony Blair as prime minister, Gordon Brown.
Calling for power to be localised, he liked the Labour Government to the hurricane which has hit the Azores.
"A great, grey depression that spins around, sucking everything into its centre. And its name? Hurricane Gordon."
Sir Menzies turned his fire on the Conservatives too, accusing David Cameron of being "a substance-free zone". "Their idea of political principle is to say, tell us what you don't like and we'll abandon it," he said.
He demanded Mr Cameron apologise for supporting the Iraq war and for writing "one of the most reactionary, unpleasant, right-wing manifestos of modern times" at the last election.
The Lib Dems are trying to sell Sir Menzies' personal story and the leader began his speech only after a slideshow about his personal life.
Set to pumping music, it screened photos of him as an Olympic athlete in the 1960s, a successful barrister, husband and energetic campaigner.
Sir Menzies gave more details of his background, telling how he had grown up in a Glasgow tenement with his parents working hard to give him they chances they never had.
"But opportunity should not be an accident of birth," he said: "It must be open to everyone in Britain."
The 65-year-old said his generation were now "entering what I like to call youthful middle age".
He received a lengthy standing ovation as he was joined on stage by his front bench team and his wife Elspeth as the Brighton conference came to an end.