15 Stefanidi, E., Leonidis, A., Partarakis N., & Zabulis, X. CasandRA: A screenplay approach to dictate the behavior of Virtual Humans in AmI Environments. In Proceedings of HCI International 2019 (21st International Conference on Human-Computer Interaction), (pp. 57-66), Springer CCIS 1088, Orlando, Florida, USA, 26-31 July. 2019 Intelligent Conversational Agents are already employed in different scenarios, both in commerce and in research. In particular, they can play an important role in defining a new natural interaction paradigm between them and humans. When these Intelligent Agents take a human-like form (embodied Virtual Agents) in the virtual world, we refer to them as Virtual Humans. In this context, they can communicate with humans through storytelling, where the Virtual Human plays the role of a narrator and/or demonstrator, and the user can listen, as well as interact with the story. We propose that the behavior and actions of multiple, concurrently active Virtual Humans, can be the result of communication between them, based on a dynamic script, which resembles in structure a screenplay. This paper presents CasandRA, a framework enabling real-time user interaction with Virtual Humans, whose actions are based on this kind of scripts. CasandRA can be integrated in any Ambient Intelligence setting, and the Virtual Humans provide contextual information, assistance, and narration, accessible through various mobile devices, in Augmented Reality. Finally, they allow users to manipulate smart objects in AmI Environments. https://link.springer.com/chapter/10.1007/978-3-030-30712-7_8