From classic fairytales and Roald Dahl favourites - to Harry Potter characters and comic book superheroes – parents have pulled out all the stops to dress up their children this year.
World Book Day is an annual event run by a charity that operates in the UK and Ireland celebrated in 100 countries around the globe.
Its mission is to promote reading for pleasure by offering every child and young person the opportunity to have a book of their own.
Here are a selection of photos of youngsters celebrating World Book Day, which were sent in to the Boston Standard.
9. Pioneers Academy
Thumbs up for these books. Photo: Image supplied
10. Old Leake Primary Academy
Children pick a book to enjoy on World Book Day. Photo: Image supplied
11. Carlton Road Academy
Colourful characters from World Book Day. Photo: Image supplied
12. Fishtoft Academy
Colourful characters from World Book Day. Photo: Image supplied