Our research on Interactive Drama aims at conciliating interaction and story at the deepest level, the level of action. From a given story representation formalism, a set of elementary narrative structures is derived in order to capture the minimal requirements for providing a narrative and interactive experience to a user. Some of these structures are implemented and simulated, to illustrate the quality and limitations of each structure. Categories and Subject Descriptors I.2 [Artificial Intelligence]: Natural language processing – discourse, language generation; Applications and Expert Systems – games. J.5 [Arts and Humanities]: Literature, Performing arts. General Terms Algorithms, Design, Human Factors. Keywords Human Computer Interaction, Narrative Intelligence, Interactive Narrative, Interactive Drama, Narrative Structures.