A relevant challenge in virtual reality is to create Virtual Environments (VEs) inhabited by realistic and interactive virtual humans. Realism should ideally be achieved in all aspects of modeling , i.e. geometric, kinematic, physical, behavioral and cognitive. Our research is focused especially at two goals: (i) proposing techniques and tools for the least explored modeling aspects, i.e. the cognitive and behavioral ones, (ii) developing new applications of virtual humans. With respect to the first goal, we are working at modeling personality of virtual humans to make the behavior of virtual humans dependent on their personality traits, as it happens with real humans. With respect to the second goal, we have employed and experimented virtual humans with different roles ranging from guides in 3D virtual museums to teachers of sign languages or nurses and patients in emergencies. We have also developed a garment prototyping application based on virtual humans (together with the Benetton group).