Measures aimed at fixing Britain's "broken housing market" are being unveiled by ministers.
Communities Secretary Sajid Javid is saying the proposals will help people currently priced out of buying a home, and bring more stability to renters across England.
The white paper being launched Tuesday outlines a new Lifetime ISA to help first-time buyers save for a deposit, and extends Right to Buy discounts to housing association tenants.
The Government will also consult on measures "to tackle all unfair and unreasonable abuses of leasehold", and move to reduce the number of properties left standing empty.
Mr Javid is saying a whole generation risks being "left behind" due to soaring prices.
"Walk down your local high street today and there's one sight you're almost certain to see. Young people, faces pressed against the estate agent's window, trying and failing to find a home they can afford.
"With prices continuing to sky rocket, if we don't act now, a whole generation could be left behind. We need to do better, and that means tackling the failures at every point in the system.
"The housing market in this country is broken and the solution means building many more houses in the places that people want to live.
"Today we are setting out ambitious proposals to help fix the housing market so that more ordinary working people from across the country can have the security of a decent place to live.
"The only way to halt the decline in affordability and help more people onto the housing ladder is to build more homes. Let's get Britain building."
The white paper states that "only in exceptional circumstances" can local authorities alter Green Belt boundaries.
A £3 billion home-building fund aims to help small firms as 60% of new dwellings are currently constructed by just ten companies.
The Communities Secretary said the fund will help build more than 25,000 new homes by 2020, and up to 225,000 in the long term by providing loans for small firms and custom builders.
From next April a Lifetime ISA will be launched aimed at supporting younger adults to save flexibly for the long term by giving them a 25% bonus on up to £4,000 of savings a year.
The Government said the extra £1.4 billion announced in the Autumn Statement will boost the Affordable Homes Programme and initiatives like the Rent to Buy scheme.
Ministers say they want more security for renters with longer-term tenancies in the private sector.
The white paper includes measures to more accurately reflect housing need in the future, giving councils revised powers to speed up the building of new homes, and to place developments where they are most needed.
Labour's shadow housing minister John Healey said: "The measures announced so far in Theresa May's long-promised housing white paper are feeble beyond belief.
"After seven years of failure and 1,000 housing announcements, the housing crisis is getting worse not better."