This article sets out what is known of the life of Giambattista Tolomei (1653–1726), sometime rector of the Jesuit school in Ragusa (Dubrovnik), of the Collegio Romano, and the Collegio Germanico, cardinal of the Holy Roman Church, philosopher, theologian, bibliophile, and philologist. Tolomei’s life intersected a series of significant events in the church’s history and that of the Society of Jesus: on-going conflict with Jansenism, the Chinese Rites controversy, significant innovations in the Society’s intellectual curriculum, and its renewed incorporation within the upper echelons of the Roman Curia. Tolomei played a key part in all those developments, and his role in what transpired is explored here—placed in context to establish his significance to the Society’s history in the early eighteenth century and beyond.