Virtual Reality (VR) has caught the imagination of many people. Frequent reports in the popular and technical press describe the hardware and software that permit people to "enter" a computer-created "world" and give accounts of what the VR experience is like. Invariably, these reports end with claims for the applicability of VR to all manner of activities, including education. This paper discusses the potential value of VR to education. It does so in the light of research conducted at the Human Interface Technology Laboratory at the University of Washington and on the basis of recent developments in cognitive theory that are relevant to human learning. The case is made that immersive VR offers very different kinds of experience than those students normally encounter in school. The psychological processes that become active in immersive VR are very similar to the psychological processes that operate when people construct knowledge through interaction with objects and events in the real world. Such a convergence of learning processes with experiences permitted by technology is relatively rare and requires that we rigorously examine both the psychological and the technological sides of the equation. This paper therefore starts with a description and analysis of VR. It then describes recent psychological theories of knowledge construction. Finally it examines the nature of the confluence of VR and constructivist learning theory -- the "goodness of fit" between the two, concluding that constructivism is the best basis for building a theory of learning in virtual environments.