Pupils from disadvantaged backgrounds often go hungry instead of claiming free school meals for fear of being bullied, according to a new report.
An inquiry into child poverty in Wales found that a third of Wales's poorest secondary school pupils would rather go without food than risk the derision of their peers.
The report, by the Assembly's cross-party children and young people's committee, said pupils should be able to claim free school meals without fear of stigma, and recommended that clear guidance on implementing a stigma-free system is given to all schools by September.
"It is imperative that this issue is addressed without delay," it said. "In the current economic climate, more families will be struggling to provide for their children, making it all the more important that all those who are eligible for free school meals receive them."
The report said schools have a key role in eliminating the effects of child poverty through education, but admits they cannot succeed alone.
Schools must believe they can make a difference and strong leadership is vital to nurture that belief, it said.
Last week, the Assembly government launched its final Child Poverty strategy and reaffirmed its goal to eradicate child poverty by 2020.
The strategy said too few schools are effectively supporting their most disadvantaged pupils.
An Assembly government spokesman said: "It's important that children and young people entitled to free school meals are not stigmatised.
"Local authorities and schools can, if they wish, put in place cashless systems to purchase school meals and we would encourage this.
"We have made a clear commitment to doing everything within our power and using every lever available to us to achieve our 2020 goal."