Ed Miliband today accused the Government of taking "backward steps" on social mobility by allowing inequality to grow and denying bright youngsters from poor backgrounds the chance to succeed.
The Labour leader called for action to open up the "closed circles" in elite professions and make it easier for disadvantaged children to go to university.
But he also attacked the "snobbery" that suggests only an academic education is worthwhile, insisting that the UK must give more respect and value to vocational learning and apprenticeships.
Mr Miliband called for a "new bargain with employers", with Government offering the right support and incentives for them to deliver good training for long-term high-value jobs.
And he denounced the Beecroft Report, currently being considered by ministers, which proposes instead reforms of labour laws to make it easier for employers to hire and fire workers.
"The countries that succeed in having a higher-skilled, higher-paid workforce are those where employers and employees show commitment to each other," said Mr Miliband.
"This is the opposite to what this Government wants to do - now considering a proposal from the Beecroft Report to make this short-term culture worse by allowing employees to be fired at will.
"We need an economy based on long-termism, investment, and training.
"Not the short-term, fast buck, take-what-you-can culture that caused the financial crisis in the first place."
Mr Miliband admitted the previous government should have done more to tackle social mobility but insisted the problem did not get worse under Labour, arguing that the measures it had put in place focused on early intervention so the results would not be seen for many years.
He told the Sutton Trust's conference on social mobility: "The reality is that governments have not got this right for decades.
"It's not just about qualifications, it's about the culture of the country and what it celebrates and what it doesn't."
Mr Miliband defended the previous government's commitment to 50% enrolment of young people to higher education but admitted Labour had failed to help those who did not continue their studies.
"I think the target was right but we didn't do enough to focus on the 50% that didn't go to university."
Asked if he would consider means-testing tuition fees, the Labour leader told the London forum all options would be considered when the party drew up its next manifesto.
Mr Miliband called for an end to the view that vocational education was second-class.
"Social mobility must not be just about changing the odds that young people from poor backgrounds will make it to university," he said.
"That really matters. But we also have to improve opportunities for everyone, including those who don't go to university.
"We must reject the snobbery that says the only route to social mobility runs through university, as if only one kind of pathway to success matters.
"In Germany, middle-class parents boast about their kids doing great apprenticeships.
"But in Britain, too often people think that if they don't go to university, they are written off by society.
"We must have a better offer to those young people. So how do we do this?
"The first issue is that for far too long we have treated vocational subjects as second-class, separate and unequal, and it is getting worse."
He added: "We need to ensure vocational education is seen as just as much of a gold standard as academic education."
Deputy Prime Minister Nick Clegg will dismiss Mr Miliband's criticism in a speech to the same conference tomorrow.
He will insist that social mobility is the "impulse" that lies behind the Government's education reforms, including the pupil premium.
And he will promise to address the "corrosive" rift in Britain's education system, citing new government data showing that children who are educated privately are three times more likely than state pupils to attain top A-level grades.
"Education is critical to our hopes of a fairer society," he will say.
"Right now there is a great rift in our education system between our best schools, most of which are private, and the schools ordinary families rely on. That is corrosive for our society and damaging to our economy.
"I don't for a moment denigrate the decision of any parent to do their best for their child, and to choose the best school for them. Indeed, that aspiration on behalf of children is one of the most precious ingredients of parenthood."
The Liberal Democrat leader will go on: "But we do need to ensure that our school system as a whole promotes fairness and mobility, that heals the rift in opportunities.
"We are committed to narrowing the gap in our school system - state and private - and ensuring that all children are given the chance to rise. The way to do that is to make the state education system better - to level up - and ensure that anyone can get ahead."
He is expected to reaffirm the coalition's drive on reforming the pre-16 curriculum, plus improve teacher and school quality.