Secondary school pupils placed in low-ability sets often feel stigmatised as "thick", a study suggests.
The government says dividing pupils into sets raises standards
Researchers at London University's Institute of Education said the system had to change to ensure these children did not lose motivation.
A survey of 5,000 pupils found they largely backed setting, but those in lower groups were more likely to prefer mixed-ability classes.
The government said "effective" setting raised overall academic standards.
The researchers found 62% of pupils preferred to be in sets, while 24% wanted mixed-ability classes.
But children's feelings were linked to their position in the hierarchy.
A greater proportion of those in the lower sets for mathematics, for example, preferred mixed-ability classes compared with those in the middle or top sets.
In the highest sets, 79% of pupils preferred setting, 67% of those in the middle sets, and 44% of those in the lowest sets.
The pattern was similar in English and science, though in those cases there were small majorities in favour of setting even in the low ability groups (55% and 54%).
Pupils who preferred setting said it meant they could work at an appropriate level. This was more important than being in a class with their friends.
But those who preferred mixed-ability teaching said it helped develop social skills and co-operation between pupils.
Setting made children in the bottom groups feel like giving up, the report said.
So they tended to prefer mixed-ability groupings.
"This finding is hardly surprising given the evidence that being in a low set limits educational opportunities, offers a more restricted range of learning experiences and carries with it the stigmatisation of being labelled 'thick'."
Professor Susan Hallam, who co-wrote the report with Professor Judith Ireson, said: "The research demonstrates that young people are mainly concerned with being able to learn.
"This is more important to them than being with their friends. If work is too easy or too difficult, the extent to which learning can take place is limited.
"Schools need to find ways to ensure that work is set at the appropriate level."
The report suggests bringing in more mixed-ability classes but with pupils working at different levels within them.
Alternatively, it proposes a "modular" system, with pupils being grouped by academic progress rather than age.
This is already in place at Bridgemary School, a comprehensive in Gosport, Hampshire.
Conservative leader David Cameron has hinted that his party might adopt such a system as its policy.
A Department for Education and Skills spokesman said: "Effective grouping of pupils by ability can raise standards and better engage pupils in their own learning.
"We have encouraged schools to use setting since 1997, and will continue to do so.
"Of course it is for individual schools to decide how and when to group and set pupils according to their pupils' needs."
He added: "Massive investment in personalised learning, as well as reforms to 14-to-19 education will deliver catch-up classes, challenge for gifted and talented pupils, and a new curriculum to keep all pupils engaged and excelling in learning."
Shadow Schools Minister, Nick Gibb, said mixed ability classes had been the scourge of the comprehensive school system since the 1970s.
"This system fails to stretch the most able and it leaves the less able floundering without the time and space to learn. Even today 60% of lessons take place in mixed ability classes.
"The evidence is overwhelming: children who are taught with other children of a similar ability find this raises achievement, raises the self esteem of the less able and results in better behaviour."
The institute's study involved pupils in 45 mixed gender comprehensive schools in London and the southern counties of England, East Anglia and South Yorkshire.
The report - Secondary School Pupils' Preferences for Different Kinds of Structured Grouping Practices - is published in the British Educational Research Review.