This paper summarizes our NSF funded project, a PC-based multi-user learning environment: Multi-User Virtual Environment Experiential Simulator (MUVEES). The goal of this project is to create and evaluate graphical multi-user virtual environments that use digitized museum resources to enhance middle school students? motivation and learning about science. Here, we discuss the design, implementation, and applications of MUVEES. We present its structure, efficient approaches that achieve more realistic avatar behaviors, and pedagogical strategies that foster strong learning outcomes across a wide range of individual student characteristics. Our preliminary results indicate that MUVEES is a powerful vehicle for collaboration and learning. We believe that our system and implementation methods will help improve future multi-user virtual environments.