Up to 2,000 vulnerable children should be given places in boarding schools, rather than going into social service care, said Ian Power, head of Lord Wandsworth College in Long Sutton, Hampshire.
Mr Power, who is also chairman of the Society of Headmasters and Headmistresses of Independent Schools, will use the society's annual conference next week to encourage schools to support vulnerable children. "We have children at my school who would otherwise be in local authority care," he said. "I know how successful it can be."
Research by the Royal Wanstead Children's Foundation found that 85 per cent of vulnerable children given assisted boarding places reached the same or higher standards as fee-paying pupils within three years. The charity said there was space for 2,000 at-risk boarders in existing schools.
Lord Wandsworth College, where fees are up to pound;22,515 a year and which counts rugby international Jonny Wilkinson among its former pupils, offers free places to around 50 boarders. The places, which cost the school's foundation around pound;700,000 a year, are given to children who have lost at least one of their parents.
A pathfinder scheme, launched by the Government to put at-risk children in state and independent boarding schools, has failed to place as many pupils as had been hoped. Numbers have been limited due to the complex decisions involved in placing children and problems with funding. Mr Power urged ministers not to abandon the pilot because of initial slow progress.
"It would be a great shame if it was stopped because it is decided that it is too complicated to administer," he said.
"It will take time to build up, but we should be placing many hundreds of children in boarding schools, not just a few dozen.
"All independent boarding schools should see if they can offer places. They have to be 100 per cent committed to it because it is not easy."
The call comes as independent schools come under scrutiny from the Charity Commission. They will have to demonstrate they are benefiting children from poor families in order to retain their charitable status, worth pound;100 million a year in tax breaks. The commission expects to publish consultation guidance for schools within the next two weeks.