This study comprises a critical edition of the complete text of Giraldi's "Altile". (The play has been published once only before the present edition, in 1583, ten years after the author's death.) This edition also contains its narrative source, Giraldi's novella (Hecatommithi, II, 3). The text shows how Giraldi telescoped his unwieldy novella into the formal neoclassical structure of Renaissance tragedy, reinterpreting or even ignoring the precepts of Aristotle when they conflicted with his experience as a practical dramatist writing for the duke and court of Ferrara. He greatly developed the characters of his leading personages, adding an important new character-type to the cast: the first scheming and treacherous subordinate of modern tragedy. The study stresses the importance of the elements of suspense, pathos and maraviglia, and the pains Giraldi took to provide his audience with a lavish, well-staged spectacle. It also emphasizes the fact that the play was intended to convey a series of clearly-defined moral messages.