Little progress has been made to close the achievement gap between rich and poor pupils, official figures show.
Eligibility for free school meals is seen as an index of deprivation
Children from poorer homes eligible for free school meals in England are almost half as likely to get good GCSE results as pupils from richer homes.
Nearly a third (32.6%) of poorer children get five good GCSEs compared to 60.7% of more affluent children, against a national average of 56.9%.
The achievement gap narrowed 0.9 percentage points on last year.
In 2005, some 29.9% of pupils on free school meals achieved five good GCSEs compared with 58.9% of pupils not eligible for the means-tested benefit in schools.
Education minister Andrew Adonis said there was some good news on the government's efforts to address social mobility - with pupils on free school meals improving faster than average.
These pupils improved by 2.7 percentage points at GCSE between 2005 and 2006.
Those not on free school meals improved by 1.8 percentage points over the same period.
The average improvement at GCSE was two percentage points.
Lord Adonis said: "We are putting a relentless focus on the progress of every individual through personalised learning so that we know exactly where progress is made and where children are falling behind."
He said an investment of £1bn would help make teaching tailored to the individual a reality and enable more intensive support for those lagging behind their classmates.