Students of English drama have long been interested in the Parnassus trilogy, produced in St. John's College, Cambridge, at the turn of the sixteenth century. The third play, The Reiurne from Parnassus, or The Scourge of Simony, was the only one published contemporaneously. Since the Reverend W. D. Macray's edition of the entire series in 1886, following his discovery in the Bodleian of a manuscript copy of the long-lost first two plays, the trilogy has been acclaimed as “the most brilliant product of the Tudor university stage.” Successive scholars have analyzed its sources, argued the problems of its authorship and dating, and variously interpreted its personal satire and allusion. Still unsolved, however, is the problem of authorship; still uncertain the answer to a famous crux in Shakespearean scholarship—the identification of Shakespeare's “purge” of Jonson, alluded to in the third play. It is the purpose of this paper (1) to introduce a new name in connection with the authorship of the trilogy; (2) by means of previously unused internal evidence to establish beyond any possibility of doubt J. B. Leishman's well-reasoned, but nevertheless inconclusive, identification of the “purge” with Dekker's Satiro-Mastix, despite the Parnassus poet's attribution of it to Shakespeare; and (3) to use this same internal evidence to reveal the Cambridge playwright's hitherto unsuspected satire of Jonson.