This volume is a translation of the first twelve chapters of The Glorious Esoteric Community Great King of Tantras (Sri Guhyasamaja Maha-tantra-raja), along with the commentary called The Illuminating Lamp (Pradipoddyotana-nama-tika), a commentary in Sanskrit on this tantra by the seventh-century Buddhist intellectual and tantric scholar-adept Chandrakirti. Regarded by Indo-Tibetan tradition as the esoteric scripture wherein the Buddha revealed in greatest detail the actual psycho-physical process of his enlightenment, The Esoteric Community Tantra is a preeminent text of the class of scriptures known to Indian Buddhist scholar-adepts as great yoga tantra, and later to their Tibetan successors as unexcelled yoga tantra. The Illuminating Lamp presents a system of interpretive guidelines according to which the cryptic meanings of all tantras might be extracted in order to engage the ritual and yogic practices taught therein. Applying its interpretive strategies to the text of The Esoteric Community Tantra, The Illuminating Lamp articulates a synthetic, "vajra vehicle" (vajrayana) discourse that locates tantric practices and ideals squarely within the cosmological and institutional frameworks of exoteric Mahayana Buddhism.