On Diary is the second collection in English of the groundbreaking and profoundly influential-work of one of the best known and provocative theorists of autobiography and diary. All the essays display Lejeune's expertise, eloquence, passion, and humor as a commentator on the functions, practices, and significance of keeping or reading a diary. Two substantial introductory essays by Jeremy Popkin and Julie Rak place his work within the fields of life writing, literary genetic studies, and cultural studies.