Almost a quarter of young people now receive private tuition outside of school time, according to research.
Rising numbers of families are opting to pay for additional help for their youngsters to help them to do well in their academic work, a survey by the Sutton Trust has found.
It reveals that 24% of 11 to 16-year-olds in England and Wales say their parents have hired a private or home tutor for them at some point in their school careers.
This is up from 23% who said the same last year, and 18% in 2005.
The poll, conducted by Ipsos Mori, also shows that children are more likely to get extra help with their schoolwork if they live in certain areas of the country.
Two in five (40%) of those living in London had received private tuition at some point, the findings show, along with around 37% of those in the east of England and 27% of children in the South East.
But only 9% of secondary school children in Wales had been given extra lessons, alongside about 8% of youngsters from the north east of England.
Sutton Trust chairman Sir Peter Lampl said: "Private tuition is booming, particularly in London, despite the fact that many families have been forced to tighten their belts over recent years.
"Parents naturally want to do the best for their children. Providing private tuition for them puts those children whose parents can't afford it at a disadvantage. That's why it is so crucial that we find a successful way to ensure that the learning gap is narrowed for less advantaged children."
He said the trust's work at the Education Endowment Foundation with the Tutor Trust aims to bring one-to-one and small group tuition to pupils from low and lower middle-income backgrounds. The Tutor Trust selects and trains university students and recent graduates to provide tuition in challenging schools. These tutors are paid for their work, although one in every seven lessons they give is free of charge.