The article analyses the early development of Aleister Crowley’s (1875–1947) Gnostic Catholic Mass and its c. 1917 German translation by Theodor Reuss (1855–1923), the founder and first international head of the initiatory fraternity Ordo Templi Orientis. Crowley’s Gnostic Mass is an influential and important example of esoteric group ritual still celebrated across the globe today. Reuss’s translated ritual holds historical interest, being the first published version of the ritual (1918) and containing a number of editorial innovations. The article discusses Crowley’s and Reuss’s collaboration and their respective masses in context, suggesting Reuss’s innovations to the Gnostic Mass shed light on his own interests in phallicism and neo-Gnosticism as well as his wish to promote Crowley’s teachings to the continental European esoteric milieu.