By Katherine Sellgren
BBC News education reporter, at the ASCL conference
The school report cards will assess a number of areas
Schools in affluent areas must do more to raise the achievement of pupils from poorer backgrounds, Schools Secretary Ed Balls has said.
Addressing head teachers, he said all schools can help break the link between deprivation and under-achievement.
He said 28% of all secondary school pupils in England entitled to free school meals went to schools with below average levels of deprivation.
But the Tories say too many pupils from poorer backgrounds still under-achieve.
Mr Balls said a new report card system, which will give schools an overall grade, would measure the progress of every child, not just the average.
Speaking at the annual conference of the Association of School and College Leaders (ASCL), Mr Balls said faster progress had been made by schools with the highest levels of free school meal pupils.
Of the 20 local authorities making the most progress, nine were in the most deprived 10% of the country, he said.
He said that pupils entitled to free school meals now had a 35% chance of attaining a GCSE in maths at grade A*-C, compared to a 25% chance in 2004.
And on the measure of five good GCSEs, the gap had narrowed by 4% since 2002, he said.
Pockets of deprivation
Mr Balls stressed that tackling deprivation was a concern for all communities.
"There are pockets of deprivation in every community," he said.
"Schools can't rest on their laurels and assume that because the majority of children are well supported at home… there aren't children who need extra support.
"We have to do more to maximise the progress of the most disadvantaged pupils in all schools and this is not just a challenge to some heads in some schools - but to all heads in all schools."
Mr Balls said new school report cards would "herald a revolution in school accountability", measuring schools on the progress of all pupils, not just the average.
Report cards will measure, among other things, how a school narrows the gap between the attainment of more affluent pupils and those with significant disadvantages or special needs.
He said this was important because existing league tables did not recognise whether schools were stretching the most gifted or helping those who had fallen behind.
BBC News website education editor Gary Eason notes that this way of measuring average improvement does not take account of the fact that it is skewed across the ability range.
Schools that were already scoring 100%, and still are, will not have shown any improvement. One that scored nothing may now be 20 percentage points better - but still have very poor results.
The methodology for the new report cards has yet to be decided, but politicians will be able to manipulate the overall scores by varying the weight given to the various elements they reflect.
Mr Balls promised detailed plans on report cards would be published in a white paper later this year.
The Conservatives say it is unacceptable that one in five pupils still leaves school without obtaining a single GCSE pass at grade C or above.
They say the progress being made by schools starting from a low level of attainment is mainly down to the expansion of the city academy programme, freeing certain schools from the control of local authorities and allowing them to focus on their individual needs.