England's education and children's services regulator Ofsted is too big to function effectively and should be split in two, MPs argue.
The Commons Education Committee is calling for it to be divided into separate inspectorates for education and children's care.
Ofsted broadened its remit to cover children's services when the Department for Education did the same in 2007.
Ofsted said any re-structuring was a matter for the government.
The government said it would consider the findings and respond in due course.
The committee reported in 2010 that the growth of Ofsted's responsibilities was causing it to "become an unwieldy and unco-ordinated body".
But this latest report goes further and says having a single inspectorate has not worked well enough to "merit its continuation".
Ofsted Chief Inspector Christine Gilbert faced criticism in 2008 about inspections of children's services in Haringey, where 17-month-old Baby Peter died after abuse.
The boy had been visited 60 times by the authorities, including child protection staff, in the eight months before his death in August 2007.
Ms Gilbert faced a barrage of questions from the same Commons committee on the standard of child protection inspections carried out by her inspectors.
This latest report argues that Ofsted has lost "elements of specialism" that were in predecessor bodies, particularly in the area of children's services and care.
It adds that different inspection regimes are needed for the different sectors Ofsted covers.
"In order to focus greater attention on children's services and care, and to ensure inspection is respected by its customers, we recommend that the government splits Ofsted into two inspectorates," it says.
A newly formed Inspectorate for Education should be responsible for the inspection of education and skills, including nurseries, schools and colleges, adult education prison learning and teacher training.
A new Inspectorate for Children's Care should focus entirely on children's services and care, including children's homes, adoption services, childminders and Cafcass, the children and family court advisory service, it adds.
And the inspectorates should ensure that they have experienced practitioners who command the respect of social workers and childcare professionals, it says.
This would improve the credibility and quality of inspection teams, the report says.
It also says too few inspectors have recent or relevant experience of the types of settings they inspect.
A sizeable percentage of the inspectorate workforce "should be experts drawn from their fields", it says.
In some regions, where inspections are contracted out to private firms or trusts, only 10% of their schools workforce are serving professionals.
This should be rapidly increased and more demanding targets need to be set, it says.
Ms Gilbert said there were many constructive recommendations in the report which she would consider.
She added: "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.
"Any proposal for further reorganisation needs to be very carefully considered and is ultimately a matter for the government."
Nansi Ellis, head of education policy at the Association of Teachers and Lecturers, said the report did not go far enough.
"It presents compelling evidence that Ofsted's school inspections should end. We too believe that a supportive local accountability system focussed on improvement rather than professional humiliation is what is needed," she said.
Association of School and College Leaders general secretary Brian Lightman said education and children's services had very different needs and priorities.
"Separating inspection of education and children's services into two divisions linked by good lines of communication is the right move and will help to ensure appropriate expertise in each area," he said.