Belles-lettres or belles lettres is a term that is used to describe a category of writing. A writer of belles-lettres is a belletrist. However, the boundaries of that category vary in different usages.

Literally, belles-lettres is a French phrase meaning "beautiful" or "fine" writing. In this sense, therefore, it includes all literary works — especially fiction, poetry, drama, or essays — valued for their aesthetic qualities and originality of style and tone. The term thus can be used to refer to literature generally. The Nuttall Encyclopedia, for example, described belles-lettres as the "department of literature which implies literary culture and belongs to the domain of art, whatever the subject may be or the special form; it includes poetry, the drama, fiction, and criticism," while the Encyclopædia Britannica Eleventh Edition describes it as "the more artistic and imaginative forms of literature, as poetry or romance, as opposed to more pedestrian and exact studies."

However, for many modern purposes, belles lettres is used in a narrower sense to identify literary works that do not fall into other major categories, such as fiction, poetry or drama. Thus, it would include essays, récits, published collections of speeches and letters, satirical and humorous writings, and other miscellaneous works. The Oxford English Dictionary (2nd Edition) says that "it is now generally applied (when used at all) to the lighter branches of literature." The term remains in use among librarians and others who have to classify books: while a large library might have separate categories for essays, letters, humor and so forth (and most of them are assigned different codes in, for example, the Dewey decimal classification system), in libraries of modest size they are often all grouped together under the heading belles lettres.

Stefan Collini (born 1947) is an English literary critic and academic who is Professor of English Literature and Intellectual History at the University of Cambridge. He has contributed essays to such publications as The Times Literary Supplement, The Nation and the London Review of Books.