Half the local authorities in England and Wales have signed up to a scheme that aims to place about 1,000 vulnerable children in boarding schools by 2018.
The positive response to the call for councils to invest in assisted boarding follows the disappointing results of Pathfinder, a similar project started by the Labour government in 2006.
The Royal National Children's Foundation (RNCF) says that its new "Assisted Boarding Network" could see about 1,000 children at risk of going into care being placed in boarding schools by 2018. The RNCF already supports 340 children in boarding schools, but local authorities currently only have 75 children in boarding nationally. Norfolk County Council alone supports 24 of these.
Labour's now-defunct Pathfinder project only managed to place 17 vulnerable children in state and private boarding schools. But Colin Morrison, chairman of the RNCF, said that the mood is now different and councils are more open to using boarding for vulnerable children.
"Times are changing. There is pressure on councils to find home and school solutions, as the cost of putting children into care is very, very high," he said. "They are reaching out and exploring these options in a way they didn't feel they needed to before."
According to the RNCF's own figures, it costs between pound;40,000 and pound;120,000 a year to place a child in care. Assisted boarding places would cost local authorities between pound;10,000 and pound;30,000 a year.
Mr Morrison said that the charity has been working hard to get local authorities on board, with countless meetings and emails. Communication, he said, would be the key to success. "There is also a difference in that we are talking to the authorities without a political agenda - we are not a political party or a business," he added. "We are specialists who understand where it works well and we know we can persuade more of them to do more."
The project has gained the support of children's minister Tim Loughton, who recently said that the government "warmly endorses" plans to promote assisted boarding through the network.
The RNCF says that it will provide expertise on best practice, develop research into the effectiveness of assisted boarding and seek increased bursaries at boarding schools. It would cost councils about pound;7 million to pound;10 million a year to support 500 assisted boarders.
The charity also aims to increase the number of children it directly supports to 500, through a patchwork of funding including bursaries from private schools. It says it is canvassing schools to help fund bursaries, but that it is "not yet quantifiable" how many will actually step forward.
William Richardson, general secretary of the Headmasters' and Headmistresses' Conference of 252 elite private schools, said that schools had "the good will and the interest" to take on children funded by local authorities, but were keen to maintain their independence. "Schools are cautious about receiving funds from state resources," he said.
Some schools with established traditions, however, are already evangelistic about assisted boarding.
John Attwater, headmaster of King Edward's School in Witley, Surrey, said that the negative attitude of some councils had come about through a misunderstanding that "you are either Hogwarts, Tom Brown's School Days or Eton".
"I don't want to generalise, but in some authorities there is the policy that you shouldn't be paying for children to go to private schools," he added.
Nick Seward, headmaster of Kingham Hill School near Chipping Norton in Oxfordshire, said that his school has benefited from taking in vulnerable children. "Many boys and girls have been able to come to my school and benefit from a stable, family-style environment where they are nurtured as individuals and achieve their potential," he said.
Other charities offering grants for vulnerable children include Buttle UK, which supports 145 children in boarding, and the Reedham Trust, which supports 130 children.
About two-thirds of the 88 local authorities signed up to the RNCF Assisted Boarding Network are due to attend the network's first conference in June.
Social mobility charity the Sutton Trust has announced that it has gained the backing of 80 leading independent day schools for a new scheme to help children from poorer families afford a private school education.
But the plan to offer thousands of means-tested bursaries needs to win government backing to the tune of pound;200 million a year to go ahead.
The trust's chairman Sir Peter Lampl said it would "transform social mobility at the top".