Colten Care’s Newstone House in Sturminster Newton hosted pupils from William Barnes Primary School.
Characters included Roald Dahl’s Matilda, Billionaire Boy, Shaun the Sheep and multiple figures from the Harry Potter books, some with wands and even owls.
Staff members also dressed as book characters including Little Red Riding Hood and Mary Poppins.
After telling their hosts all about their favourite books the children joined them for tea, squash and biscuits.
Elaine Lunn of Newstone House Companionship Team said: “It was wonderful for the residents to see the children in their special costumes and to hear about their favourite books.
“They were especially interested to hear about Harry Potter and all the magic he and his friends get up to.”
World Book Day is an annual UNESCO-recognised celebration of reading held in more than 100 countries.