This essay aims to investigate the extent to which a book’s peritext can be used to determine which age-group a book is best suited for. This in the hopes of finding a useful complement to the bibliographic information that is usually used for information retrieval, a complement that can simplify the process by adding more subject signifiers to an information retrieval system’s repertoire. The material being used is a selection of books that were published or republished between the years 2014-2020 and catalogued by the National Bibliography as belonging to the fantasy fiction genre.  The study is grounded in Gérard Genette’s concept of peritext, defined as the information surrounding a written text with the purpose of introducing the text before the actual reading commences. A number of these peritextual elements are studied to see how frequently they appear in the present study’s selection of books, after which the books’ cover designs and titles are studied in more detail. The results of this study show that there are differences in how the peritext of children’s and adults’ books are formatted, especially when it comes to how the front covers are designed. It is not, however, possible to draw any definite conclusions regarding how the peritext might be used to facilitate the process of information retrieval. To achieve this there is need for further research on the subject.