Far from being cut-down versions of the adult form, children’s dictionaries constitute a distinct genre with their own history and methodology. The chapter charts their development, from Renaissance bilingual dictionaries to the present day, showing how they have evolved to reflect changing perceptions of childhood. It discusses the bewildering range of dictionaries now available for children as they progress from ABCs and picture dictionaries to those for school use and creative writing, including innovative subgenres based on fictional worlds and dictionaries supporting language revitalisation. Drawing on historical and contemporary examples, the chapter explores content and page design adapted to engage young readers. It considers how lexicographers aim to reflect the world as experienced by children, from the selection of headwords to the framing of definitions, using dedicated corpora and reading programmes. The tension between descriptive and prescriptive approaches is often acute in children’s dictionaries, for example over the inclusion of slang and taboo words, and lexicographers aim to balance young dictionary users’ needs against adult perceptions of what a children’s dictionary is for.