Research, led by Cardiff University, suggests some Welsh school children are worse at reading than their peers in England.
The study compared literacy levels at the age of 3 when they were roughly the same.
Then again at 5 when Welsh pupils were lagging slightly behind.
At age 7 Welsh pupils had fallen behind again.
The Welsh Government says it's already introducing measures to improve literacy and numeracy.
Books by Cardiff-born Roald Dahl have dominated a list of primary school teachers' favourites to read to their classes.
In the survey, Dahl - who grew up in Llandaff - also emerged as teachers' favourite children's author.