The early-sixteenth-century Florentine Portrait of a Woman (La Monaca) and its cover (tirella), embellished with grotteschi and a mask, have puzzled and intrigued scholars since both panels entered the collections of the Galleria degli Uffizi in the early and mid-nineteenth century, respectively. They garnered further interest when exhibited in Hidden Faces: Covered Portraits of the Renaissance at New York’s Metropolitan Museum of Art in 2023. Despite important scholarship, which has suggested but not proven that the portrait depicts Caterina Antinori, many questions remain about the enigmatic pair and the iconography of the panels. This article examines new archival evidence and reinterprets the visual elements in the two panels to prove that the sitter is Caterina Antinori and to create for the first time a biography for her, where none had previously existed. It also identifies the notable patron of the panels and pins down the date of their commission. In the process, the discussion sheds light on the heretofore mysterious function of the portrait and the necessity for its cover, as well as on female identity and agency in Florence during the early Cinquecento.