Abstract: Interface agents are more and more often leaving laboratories to be used as commercial products. We can see them presenting news on the Internet or as tour guide in 3D worlds. These agents present a new opportunity for authors to create a new kind of presentation, more attractive and interactive. However, as many interface agent systems are now available, controlling them needs advanced knowledge of programming languages such like JavaScript or Visual Basic script. Our motivation is to provide classical author with a powerful but easy-to-use language to control interface agents: Multimodal Presentation Mark-up Language (MPML). Our main focus has been to provide emotional control on the agents to make the communication with the user even more natural.