Schools watchdog Ofsted has become unwieldy and must be split in two, MPs have warned.
The inspectorate has grown "too big" as it has taken on more responsibility and is no longer able to operate as efficiently as smaller organisations could, according to a report by the Commons education select committee.
Ofsted now has responsibility for inspecting children's services, including areas such as social care and adoption agencies, as well as schools.
In a report on the role and responsibility of Ofsted, the cross-party group of MPs concludes that splitting the inspectorate in two would boost confidence in inspections. It calls for the creation of an Inspectorate for Education and a separate Inspectorate for Children's Care.
"We believe that having a single children's inspectorate has not worked well enough to merit its continuation," the report says, adding: "Ofsted has grown too big to discharge its functions as efficiently as smaller, more focussed and specialist organisations might."
The report also warns that too few inspectors have recent and relevant experiences of the type of institutions they inspect.
The committee concludes that the two new inspectorates should remain independent of Government, but calls for ministers to create two new positions - Chief Education Officer and Chief Children's Care Officer - to work alongside them.
Graham Stuart, chairman of the committee, said: "Ofsted's reach is vast and its remit has grown substantially since its inception, but this has come at the expense of providing a more specialised service. We need a radical shift in how inspection operates in this country, with a more proportionate, specialist and focussed approach."
Barnardo's deputy chief executive Jane Stacey said, "Acknowledging development and looking at how far a child has come is crucial. The proposal for Ofsted to prioritise measuring pupil progress is one that complements Barnardo's ongoing commitment to improving the lives of the most disadvantaged and vulnerable children and young people."
Ofsted chief inspector Christine Gilbert said: "The question of 'who inspects?' is much less important than the quality of inspection and the impact it has on raising standards and improving people's lives. Ofsted is proud of the work it's done across the whole of its remit since it took on its present brief in 2007."