In Vivo Exposure Therapy (IVET) has been a recommended protocol for the treatment of specific phobias. More recently, several studies have suggested that Augmented Reality Exposure Therapy (ARET) is a potentially effective technology in this field. The objective of this paper is to report the preliminary results of a comparative analysis of ARET and IVET applied to the treatment of phobia to small animals. To analyze participants’ activity, we have adopted a multidisciplinary and mixed perspective based on clinical and user-centered approaches. This pilot results show that ARET and IVET are both clinically effective. Both therapies produce a significant reduction in the clinical outcome measures and allow the clients to interact with a real phobic stimulus after the therapeutic session. The results also show some main differences between technology-mediated therapy and traditional non-mediated therapy. We discuss these results in terms of future design and evaluation guidelines for Mental Health technologies.