Virtual Reality (VR) is a new technology halfway between television and computer. It constitutes another step in the evolution of our use of a tool that allows us to see, to hear and to feel in a world created graphically in three dimensions, and to interact with it. VR is, mainly, a mental experience which makes the user believe that "he is there", that he is present in the virtual world. With this new tool, the user is no longer a mere observer of that which is happening on a screen, but he "feels" that he is immersed in that world and participates in it, in spite of the fact that they are spaces and objects that only exist in the memory of the computer and in the user's mind. This chapter seeks to carry out different reflections at different levels. First, we will analyze the relationships between VR and Psychology, one of the disciplines that has made more efforts in order to understand how we obtain knowledge from the world and from ourselves. We will also analyze the impact VR can have in one of the applied disciplines of Psychology, which is Clinical Psychology. With regard to this application environment, VR becomes a tool which can generate useful models for Psychology (both normal and abnormal), and it is offered as a research context for Clinical Psychology; as a "realistic" laboratory where we can study behaviours, emotions, thoughts, etc.; and a new means to develop psychological treatments.