“Urgent steps” are needed to ensure more effective support for two million disadvantaged pupils in England, a report from a committee of MPs warns.
The Public Accounts Committee said there was a lack of consistency in funding and levels of support.
The MPs called for a “better understanding” of what worked to close the gap between rich and poor pupils.
A Department for Education spokesman said the government was committed to tackling “educational inequality”.
Closing the “attainment gap” for disadvantaged pupils should be a “cornerstone of education policy”, said Meg Hillier, who chairs the committee.
The Public Accounts Committee, which scrutinises the value of public spending, said there were early signs that pupil premium funding was making a positive difference.
But it called for a “step change” in increasing efforts to prevent poorer pupils from losing out at school.
Ms Hillier said without closing the attainment gap, poverty would continue to “pass down through generations”.
“There needs to be a better understanding of why disadvantaged pupils from different backgrounds can perform so differently,” she said.
The report highlights how underachievement seems to be more deeply entrenched for some pupils, such as those in deprived coastal areas.
In contrast, it said that Chinese pupils had high levels of attainment “irrespective of their level of disadvantage”.
Pupil premium funding has provided £6bn support for poorer pupils between 2011 and 2015.
But the committee wanted more sharing of how pupil premium money could be used most efficiently.
And it highlighted differences in school funding, which could mean that “some schools receive about £3,000 a year more than others per disadvantaged pupil”.
The committee also said it was “very concerned” that the rollout of universal credit did not include a clear mechanism for identifying children eligible for the pupil premium.
Sir Kevan Collins, chief executive of the Education Endowment Foundation, supported the committee’s call to “encourage schools to use evidence-based interventions to make sure the pupil premium is being spent in the most effective ways”.
‘Close the gap’
He said the funding system should be designed to reward schools that succeeded in helping disadvantaged pupils.
Christine Blower, head of the National Union of Teachers, said “in many cases pupil premium funding has been used to plug gaps that have occurred as a result of squeezed budgets”.
Head teachers’ leader Brian Lightman said pupil premium funding was making a positive difference.
“Nevertheless, it remains clear to everybody that much more still needs to be done on this critical issue and the highest ambition of school leaders is to close the disadvantage gap further,” said Mr Lightman, ASCL general secretary.
Labour’s shadow education secretary Lucy Powell said: “Ministers obviously still have their heads in the sand.”
A Department for Education spokesman said: “It is encouraging that this report recognises the extent to which the government has been able to narrow the attainment gap between disadvantaged pupils and their peers.
“We are determined to ensure every child, regardless of background, is given an education which allows them to realise their full potential, and we are committed to do more to tackle educational inequality.”