Virtual Reality (VR) technology has been effectively implemented in psychotherapy as an alternative to exposure. VR has also been employed in treatment of eating disorders, body image disorders etc. As with any other treatment, efficacy varies among clients. One parameter that has been suggested as increasing treatment efficacy is presence. "Presence" is the subjective experience, so that the client/subject feels as if s/he is "in" the situation even though it is not real. Presence is influenced by both personality and technological factors. This chapter presents a comprehensive review of studies examining variables impacting on presence, with the aim of elucidating the optimal VR user profile.