Jonathan Marques, 15, disappeared on his way to school in Southcote, Reading, on Tuesday, January 6.
He is 5ft tall with untidy black hair and braces on his teeth.
He was wearing a Blessed Hugh Faringdon school uniform - a maroon sweatshirt and dark trousers as well as a grey hooded top. He was carrying a rucksack.
His family is desperate to find him.
If you have any information please contact Thames Valley Police on 08458 505 505 and quote URN 406 or Crimestoppers anonymously on 0800 555 111.