The dissertation begins with a review of relevant contemporary theoretical and autobiographical considerations starting from Philippe Lejeune, Gerard Genette, Manfred Jürgenson, to Andrea Zlatar and Helena Sablić Tomić. Thereupon it systemises a corpus of prose in a diary form, intended for children and young adults, consisting of the following fifteen titles: Zora Ruklić, Iz dnevnika jedne djevojčice (From a Girl's Diary) (1938); Joža Horvat, Sedmi be (Class VIIb) (1939); Vjekoslav Majer, Dnevnik malog Perice (Pete's Diary) (1942); Ivo Ladika, Dnevnik gimnazijalke (The Diary of a High-School Girl), 22. rujna (22 September) (1963); Miro Gavran, Zaboravljeni sin ili Anđeo iz Omorine (The Forgotten Son or The Angel from Omorina) (1989), Pokušaj zaboraviti (Try to Forget) (1996); Sanja Polak, Dnevnik Pauline P. (The Diary of Paulina P.) (2000); Stjepan Tomaš, Moj tata spava s anđelima (Mali ratni dnevnik) (My Dad Sleeps with Angels – Small Wartime Diary) (2002); Sanja Polak, Drugi dnevnik Pauline P. (The Second Diary of Paulina P.) (2003); Ratko Bjelčić, „Kako da jednoj pčelici...?“ (Mali dnevnik o velikoj ljubavi) (How to Tell a Little Bee... (A Small Diary of a Big Love) (2004); Ivana Josić, Dnevnik Mile Horvat (The Diary of Mila Horvat) (2004.); Tomislav Zagoda, Balada o Buginim gaćicama (Dnevnik Gustava S.) (The Ballad of Buga’s Panties (The Diary of Gustav S.)) (2004); Ratko Bjelčić/Silvija Šesto Stipaničić, Dnevnik jedne ljubavi (The Diary of One Love) (2007.); Sanja Polak, Pobuna Pauline P. (The Rebellion of Paulina P.) (2007). Analytical research of chronologically ordered diary paradigms reveals mutual structural differences and specific features from which certain models of diary fiction may be deducted. With regard to the relation author/narrator/character, all the above mentioned examples (with the exception of Iz dnevnika jedne djevojčice (From a Girl's Diary)) contain a narrative model of homodiegetic fiction, in which the narrator is identical to the character, whereas the author is not identical to any of them, which refers to the fact that these diaries are fictional. The research has resulted in a valuable realisation that there is one non-fictional diary among the fictional ones – the one written by Zora Ruklić (Iz dnevnika jedne djevojčice (From a Girl's Diary)). The time span of the diary fiction comprises a period of approximately seventy years, and the majority of the texts were created in the period from 1989 to 2007. It has been recognised that authors of diary fiction for young adults use slang as a factor contributing to equalisation in the relation author – subject of the diary – recipient. A research conducted among respondents aged from eight to seventeen, i.e. those for whom these books are intended, has thrown light on the issue of the diary discourse in the Croatian literature for children and young adults in relation to the readers’ reception, in the sense that the achieved results confirm the selection of the examples constituting the corpus of the paper and thus justify the inclusion of several books whose genre was doubtful into the analytical and theoretical research (the recipients recognised Dnevnik Pauline P. (The Diary of Paulina P.), Mali ratni dnevnik (Small Wartime Diary) and Dnevnik gimnazijalke (The Diary of a High-School Girl) as diary fiction, and not as novels, to which category they had been classified so far in the existing theory of literature for children and young adults). Finally, the diary has proven to be an autonomous model/genre in the Croatian literature for children and young adults.