The survey says the children and young people's voluntary sector workforce totals 160,000 and generates £1.5bn a year.
The National Council of Voluntary Child Care Organisations and the National Council for Voluntary Youth Services commissioned Hull University to conduct the research. The two organisations will use the figures to impress public authorities that commission young people's services as part of the Every Child Matters agenda.
Maggie Jones, chief executive of the NCVCCO, urged the Government to take a long, hard look at what was happening on the ground in the children's sector and "develop a far more detailed understanding of the size, scope and nature" of the sector.
The survey relied heavily on data supplied by GuideStar UK. Susanne Rauprich, chief executive of the NCVYS, said the researchers had to look elsewhere for the information they wanted because it had been particularly difficult to get data on small charities from GuideStar.
Les Hems, director of third sector data and analysis at GuideStar Data Services, said GuideStar UK published details of all registered charities, but that charities with incomes below £10,000 were not obliged to publish anything other than their income and expenditure.
Hems urged charities to use the facility on GuideStar's website that enables them to add more detailed information about their activities.