Offering free school meals to everyone can help close the gap between rich and poor pupils, a report suggests.
A study looking at the effects of extending free meals to all in two pilot areas of England suggests primary pupils advance by two months on average as a result.
Advances were most pronounced in pupils from poorer homes.
Researchers put the attainment boost down to improvements in pupils' productivity.
The study looked at the impact of extending entitlement to free school meals in three English local authority areas over a two-year period.