This paper written by Marie-Laure Ryan deals with the narratological and pragmatic dimensions of Henry Jenkins’ concept of transmedia storytelling, by exploring, among other topics, its relation with adaptation and transfiction, and its top-down and bottom-up modalities, between industry control and fandom. Ryan proposes a typology of multiple modes of interaction and participation, and makes a detour through various categories of multimedia narratives, before underlining transmedia storytelling’s ability to sustain vast and complex fictional worlds.