Thousands of teenagers are being given £10 loans to see if they can both turn a profit and benefit society.
The government wants the scheme to be a "mainstream option"
"Make Your Mark With a Tenner" is part of a week of events celebrating social enterprise - a sector hailed by Gordon Brown as a "new British success story".
Funded by Andrew Reynolds, a marketing guru, the scheme allows 10,000 pupils to take the loan, create a business and try to make a social impact.
Mr Brown said £18m in government grants would be made available for projects.
Chef Jamie Oliver's "Fifteen" restaurants staffed by disadvantaged youths is seen as an example of "social enterprise".
Make an impact
It is one of the highest-profile examples of 55,000 such initiatives across the UK founded with a social purpose and reinvesting profits in the community.
The first £10 notes were made available to children in Stockwell Park School, south London, on Thursday as part of Enterprise Week.
Pupils have a month to make an impact after accepting the loan - the 50 who make the most profit and the 50 who have the biggest social impact will win prizes.
Schools and colleges distribute the money and decide on the suitability of projects - those that return less than 60% of loans will be banned from future participation.
Mr Reynolds said he had donated the money to allow young people in the UK to show they were "not all a bunch of violent hoodies".
"With the right encouragement they have the potential to be the best," he said.
The scheme was announced alongside the publication of the government's Social Enterprise Action Plan.
Chancellor Gordon Brown has said grants will be made available to fund other projects, and up to 20 "ambassadors" will act as role models to encourage young people to get involved.
The government's proposals - devised by the Cabinet Office - are aimed at making social enterprise a "mainstream option" for anyone setting up a new business.
As well as making it part of GCSE and A-level business courses, more than £18m will be made available to "help knock down barriers" and "enable social enterprises to thrive".
Mr Brown said: "In my view, social enterprise is the new British business success story, forging a new frontier of enterprise - a quiet revolution involving 55,000 social enterprises in our country from the smallest community groups to larger businesses."