A third of secondary pupils say they are streamed by ability and the proportion of teenagers being set by ability in English lessons has increased significantly since 2006, new research shows.
The Sutton Trust, which commissioned the study, believes setting is a good way of stretching bright pupils from poor backgrounds. But it is concerned that not enough of them are reaching top sets and there are fears that streaming could entrench disadvantage.
Ipsos Mori interviewed 2,700 pupils aged between 11 and 16, of whom 32 per cent said they were taught in streams - ability groups that cover most or all subjects.
A much higher 94 per cent said they were put into a "set" - an ability group covering a single subject - for at least one of the core areas of English, maths and science.
James Turner, policy director at the Sutton Trust, said: "We do have more schools that are streaming now and that could be worrying in some respects because it is like selection within a school.
"If there is a bias towards the middle classes in streaming it will operate throughout the school for pupils. At least with setting there is more flexibility."
Mr Turner said anecdotal evidence supported the idea that streaming was on the increase. But he said the poll could have exaggerated the total because pupils were not clear what the term meant.
In addition to the 32 per cent who said they were streamed, another 42 per cent said they were unsure, while 23 per cent said they were not.
In maths, 89 per cent of pupils said they were set by ability, in sciences it was 72 per cent, and half of pupils were set in modern foreign language lessons.
The results are broadly in line with a previous survey in 2006 when the figures were 89, 72 and 50 per cent respectively and no question was asked about streaming.
But for English lessons the survey found 80 per cent of pupils were now set by ability, compared with 62 per cent four years ago.
The previous Labour government supported setting and Michael Gove, the new Conservative Education Secretary is a "strong believer" in both setting and streaming in comprehensives.
Mr Turner said the trust had now commissioned academics at Durham University to research whether it was more common for middle-class pupils to get into top streams or sets, compared with more deprived pupils of similar ability.
John Bangs, head of education at teaching union the NUT, said: "There has been enormous government pressure to go in for setting and streaming, but all the evidence is that the jury is out on its effectiveness."
He said bigger secondary class sizes could also have increased setting and streaming because big mixed ability groups were generally seen by schools as harder to manage.
"The evidence with streaming, as opposed to setting, is that expectations are depressed for kids in the lower and middle streams," he said.