It has been over 40 years since the publication of Wasson’s Soma: Divine Mushroom of Immortality, and in that time his theory identifying Soma as the Amanita muscaria mushroom has remained one of the most viable proposals to date. One failure of Wasson’s, however, was to demonstrate how the preparation of Soma, as described in the Rig Veda, supported his identification of Amanita muscaria. The research presented above fills this gap by demonstrating that the effects of Amanita muscaria are related to the type of preparation employed, and that the optimal effects of Amanita muscaria are produced through preparations that parallel those described for Soma in the Rig Veda. Wasson’s theory is further supported by a reading of the Rig Veda that interprets the preparation of Soma as not merely an extraction process, but also a purifying process, since the techniques of Soma preparation when applied to Amanita muscaria not only extracted the active principles of the mushroom but also significantly reduced the presence of its nauseating and emetic properties. While this effort in no way closes the door on the debate over the identity of Soma, these findings help to solidify the foundation of Wasson’s theory, as well as demonstrate the utmost importance of preparation in understanding and uncovering the true identity of Soma.