Anxiety disorders are among the most common psychiatric disorders encountered in clinical practice, if not the most common. Standard treatment consists of psychotropic medication and psychotherapeutic interventions. A key psychotherapeutic intervention is exposure therapy. Exposure can be either imaginal, by having the patient imagine a particular scene (for instance, a traumatic war experience), or in vivo (for instance, having a patient who is afraid of flying go to an airport, watch planes take off, sit in an airplane seat, etc.). As the authors of this book point out, virtual exposure may have advantages over both imaginal and in vivo exposure. It may be superior to imaginal exposure in that it is much more life-like and therefore might be more effective. At the same time, it has many potential advantages over in vivo exposure. It is generally much less costly; it saves public embarrassment; it can be stopped if the symptoms get overwhelming. In addition, the key aspects can be repeated over and over; for instance, if someone has a fear of flying, and the therapist identifies that the take-off is the anxiety provoking aspect of flying, a virtual take-off can be replayed over and over again. Physiological monitoring of data such as heart or respiration rate is much easier to achieve during virtual than in vivo exposure. Finally, many situations that one would not replay, such as war trauma or sexual assault, can be addressed through the safety of virtual reality.