Ant?nio Carlos da Rocha CostaEscola de Inform?ticaThe SAGRES system is an environment built on the Web, that facilitates the presentation of information bases of a museum, in a way which is adapted to the individual characteristics of each visitor. The interaction with the system may occur individually or in groups of students. The system offers also resources to support some forms of cooperative learning, allowing visitors to interact both synchronously and asynchronously, and both, locally, inside the museum, and non-locally, in places geographically distant from the museum. The visitors are assisted by virtual guides that are software agents which purpose is to monitor the visitors? actions. The agents use the human-computer interaction paradigm called directed improvisation to interact with the visitor. They improvise, while helping the visitor, a group of behaviors similar to the human behaviors (happiness, satisfaction and vibration), making the interaction more friendly. This system is developed in the Museu de Ci?ncias e Tecnologia (MCT) at PUCRS, Porto Alegre, Brazil.