The history of the naturalist novel reveals shortcomings of recent proposals for the study of world literature, such as those of Franco Moretti and Pascale Casanova. After a naturalist esthetic coalesced in France in the 1860s naturalist schools appeared around the world. Contrary to what models of diffusion predict, naturalism flourished in distant parts of the world at the same time as its triumph in Europe, while writers nearer France rejected it. The examples of naturalism in Argentina, Brazil, Japan, China, and Korea, reveal multiple, overlapping histories that make up the heterogeneous planetary history of the form. Naturalism’s movement was aided by its association with non‐fictional genres such as criminology, and flourished where other forms of realistic fiction were not well established. Even when naturalism bore the standard for realism, however, it formed unexpected alliances with other esthetics and shifted its associations with non‐fictional genres. Rather than focusing on the origination and reception of forms such as the naturalist novel, studies of world literature should focus on the conditions of travel through which such unexpected transformations occur.