The number of pupils in England's state schools will grow within the decade to its highest level since the 1980s, official projections show.
The Department for Education predicts the school population will grow by a million to 8m by 2022.
The rise is due to the growth in birthrates since 2002.
The sharpest increase will be in primary schools, with a predicted 15% increase by 2020. Primary schools in some areas are already over capacity.
The figures may prompt fears of a further shortage of school places in years to come.
The National Audit Office had warned this year that an extra 240,000 primary school places would be required by next year, but the latest figures suggest demand will grow intensively in the next few years.
The government said it was working with local authorities to make more places available.
Schools Minister David Laws said: "We are spending £5bn by 2015 on creating new school places, more than double the amount spent by the previous government in the same timeframe.
"Estimates show this funding has already created 190,000 extra places, and there are many more to come.
"On top of this, we are creating 130,000 places in free schools, seven in 10 of which are in areas with a shortage. I have announced an additional 19,000 new school places in areas where they are needed most.
"We are working with local authorities to ensure funding is used to enable every child to attend a good or outstanding local school."