Cooperative learning is changing the learning environments design. Intelligent Tutoring Systems, Multi-agent Systems, Affective Computing and Virtual Characters, are techniques and resources to improve the individual and personalized learning. In this research direction, this paper presents a Socio- Affective Agent whose reasoning is based on individual aspects of the student, as affective states, personality and acceptance, and group aspects, as cohesion. This socio-affective agent is being integrated in the AMPLIA environment, an Intelligent Probabilistic Multi-agent Environment to support the diagnostic reasoning development and the diagnostic hypotheses modeling of domains with complex and uncertain knowledge, like medical area. In order to provide semantic interoperability between the environment?s agents we are using an OWL (Web Ontology Language).