A Hat Full of Sky is a comic fantasy novel by Terry Pratchett set on the Discworld, written with younger readers in mind. It is labelled a Story of Discworld to indicate its status as children's or young adult fiction, unlike most of the books in the Discworld series. The book is also a sequel to the Discworld short story The Sea and Little Fishes, which introduced the Witch Trials and Mrs Earwig. It is followed by Wintersmith.