The event has been sparking imaginations and instilling a love of reading for decades, with children and adults alike dressing up in honour of their favourite books.
See if you made our gallery below…
5. Gracie- Luna Lovegood
Rivelin Park pupil Gracie, 7, looks magic as Harry Potter's Luna Lovegood. Photo: Rosie Lines
6. Mylo- Hagrid
You're a wizard, Harry! Mylo, in Year 4 at Carterknowle Junior School, is Hagrid's double! Photo: Amanda Ellis
7. Alfie- Fantastic Mr Fox
12-year-old Alfie, who attends Bents Green Specialist School, is Road Dahl's Fantastic Mr Fox for the day. Photo: Elizabeth Holland
8. Amelia- Goth Girl
As a Year 6, 10-year-old Amelia isn't really into fancy dress these days, but she was inspired to 'dress up, while not really dressing up' by her favourite Goth Girl books. She attends Shawlands School. Photo: Georgina Shaw