Buddhist thinkers in Tibet, most especially those associated with Tibet’s Nyingma or Old School of Buddhism, have produced a rich and understudied current of tantric philosophy advancing the authority, validity, and rationality of the tantric view. This paper examines the text, Establishing Appearance as Divine (Snang ba lhar bsgrub pa) by Rongzom (fl. 11th–12th c.). It is our earliest documented instance of a Tibetan “tantric pramāṇa”—that is, an approach characterized by the philosophical integration of exoteric philosophical thought and esoteric ritual and ideology. As such, and in contrast to more narrowly focused studies of Tibetan ritual or Tibetan philosophy, this paper details the form, content, and context of Rongzom’s tantric pramāṇa or epistemological discourse in terms of both classical epistemology and Buddhist Tantra. This study thus sheds light on the relationship envisioned between ritual and philosophy in traditions of Vajrayāna.