The most successful education systems combine local autonomy for schools with strong public accountability, the OECD's education expert has told MPs.
Andreas Schleicher, in charge of the international Pisa tests, faced questions from MPs about how he thought England's academy system was working.
Mr Schleicher said the global evidence suggested local flexibility for schools was linked to higher results.
He described free-standing academies as a "promising trend".
Describing the features of the most successful education systems around the world, he praised "local discretion" for head teachers and school leaders combined with a shared expectation of high standards.
The flexibility of individual schools needed to be balanced by a strong culture of transparency and accountability, he told MPs.
The House of Commons Education Select Committee was taking evidence from Mr Schleicher in its inquiry into academies and free schools in England.
He gave his broad endorsement of the academy system in England, where state-funded schools are given more control over their budgets and flexibility over their curriculum.
But Mr Schleicher warned that autonomy on its own was not a way of improving schools.
He pointed to the example of the United States as evidence that more autonomy could be "part of the solution or else part of the problem".
In the US, the negative side could be isolation and a lack of coherence in maintaining standards, he said.
"You need a very strong education system to make autonomy work, you can't leave it to market forces alone," he told MPs.
Within Europe, he said that autonomy was linked to high performance in the Netherlands but not in Sweden, which has seen a fall in its Pisa test ranking.
He told MPs that high-performing systems had a culture of expecting good results from all pupils - and that there was nothing inevitable about the under-achievement of children from poorer families.
Within England, he commended the achievement of the former London Challenge initiative, which had seen schools in the capital improve more quickly than elsewhere in the country.
In England, academies are now the most common type of secondary school.
There have been recent disputes over whether providers that use public funding to run academy chains should face greater accountability.
Sir Michael Wilshaw, the head of Ofsted, argues that there should be inspections of academy chains in the way that inspectors can scrutinise local authorities - a proposal that the government has resisted.
Mr Schleicher was asked by MPs about whether creating such chains to run groups of academies removed the benefits of autonomy.
He said that moving decision making away from individual schools would reduce the advantage of such local flexibility and risked reducing a school's sense of "ownership".
The OECD education expert was also asked about the Pisa tests, which had seen the UK failing to improve.
He told MPs that the most successful school systems invested heavily in teacher training and professional development.
Education systems such as Shanghai and Finland require constant training and updating of skills for heads and teachers.
Another problem facing schools in England, he said was that as well as poorer results from disadvantaged pupils, many schools serving privileged areas failed to reach their potential.
Facing questions about the reliability of comparing countries with an individual city such as Shanghai, he told MPs that Shanghai had a bigger and poorer population than many OECD countries and that the statistics were robust.