Published at Venice between 1551 and 1553, Giovanfrancesco Straparola's collection of fairy tales, novelle, riddles and madrigals, Le piacevoli notti, proved a European best-seller. In the collection's loose framing narrative, set during carnival in 1530s Venice, the first tale of the final night is recounted by English ambassador to Venice, Giambattista Casali (c.1494/95–1536). Straparola's frametale has been read chiefly to illuminate the fairy tales; this article employs it to trace a set of elite Venetian social institutions and networks into which Casali successfully interpolated himself over the course of his 1526–35 embassy. Casali's initially unlikely inclusion in the Piacevoli notti demonstrates the immense practical significance of those networks to his diplomatic credibility and efficacy. Crucial to Casali's diplomatic career was his building up of political credit through informal sociability and through brokering cultural patronage between Venice, his native cities of Bologna and Rome, and the courts of Mantua, England, or Hungary. In highlighting the value of informal sociability for Renaissance diplomats such as Casali, the article contributes to calls for a broader conception of politics in the historiography of early modern diplomacy.