This article aims to identify the presence of the Florentine painter Agnolo di Domenico del Mazziere in the decorative project of the Borgia Apartments in the Vatican, executed between 1492 and 1494 under the direction of Pintoricchio and Piermatteo d'Amelia. In particular, his contribution is recognized in several figures of the 'Dialectic' lunette in the Room of Liberal Arts, and in the half-length figure of God the Father in the 'Annunciation' in the Room of Mysteries. Confirming the collaborative nature of the entire cycle, the 'Dialectic' also bears the hand of another Florentine painter, Bartolomeo di Giovanni, who was extensively active in the apartments. Agnolo's activity in Romeprovides a crucial chronological reference for the artist, who appears to have developed a personal taste for Roman antiquities and to have early absorbed the stylistic and compositional innovations introduced by Filippino Lippi in the Carafa Chapel (completed by 1493).