The number of children in schools of more than 2,000 pupils has more than trebled since 1997, the Tories say.
Ministers reject claims that big schools mean worse discipline
In 1997, 12,650 pupils in England were in secondary schools at least that big, but last year the figure was 47,540.
Nearly one in every seven pupils - 488,900 - goes to a school of more than 1,500, according to government figures highlighted by the Conservatives.
A government spokesman said UK evidence indicated achievement could increase with school size up to a certain point.
The government says a total of 69 local authority maintained secondary schools in England have 1800 pupils or more.
The Conservatives say the worst discipline problems are found in larger schools.
Shadow children's secretary Michael Gove said: "In America, cities like New York and Chicago have significantly improved behaviour and standards by encouraging smaller schools where it is easier to foster respect and the head teacher is able to know the name of every pupil.
"The [UK] government's pile-'em-high approach is letting down some of the most disadvantaged pupils."
Six out of 10 secondary school pupils were being educated in schools with more than 1,000 children in 2007, up from 46% in 1997, the Conservatives said.
A Conservative working party looking at public services put forward the idea of smaller schools as a potential policy in September.
Schools Minister Lord Adonis said: "Schools have increased in size because parents and children want to go to them.
"Labour has actively encouraged the expansion of popular and successful schools, so that more parents can choose to send their children to them.
"The Conservatives will create a huge parental backlash and rightly so if they are proposing to stop successful schools from growing."
The government has rejected suggestions that discipline is worse in very big schools.
A spokeswoman for the Department for Children, Schools and Families (DCFS) said: "British evidence is that achievement can increase as school size increases, up to a certain point.
"Large schools can be split into 'houses' or multi-site facilities where pupils can be taught in smaller units while still benefiting from the enhanced facilities that many larger schools have.
"The assertion that larger schools mean lower standards of behaviour is not supported by Ofsted inspection evidence."
The figures were released as it emerged that in some areas of England the equivalent of one out of every 20 secondary school pupils had been suspended for physical or verbal assaults against staff.
An analysis by the Daily Telegraph suggested the worst problems were found in Manchester, Hull, Poole, Bristol and Southampton.
The newspaper found the average for England of secondary pupils suspended in 2005/06 for assault or threatening an adult was 2.7%.
Figures for Southampton, Poole and Bristol were 7.2%, 5.9% and 5.5% respectively.
A spokeswoman for the DCSF said: "We should remember that violence in schools is rare.
"Clearly, any assault against a member of school staff is totally unacceptable, which is why we continue to focus on ways in which we can support schools in developing behaviour strategies to prevent this from happening."
Exclusions for attacks on adults related to just 0.12% of the school population, she said.