This dissertation examines the culture of diplomacy in Zurich during the early years of the Swiss Reformation. Its goal is to use an approach to diplomacy during the Protestant Reformation that is informed by the New Diplomatic History. Zurich diplomacy in the 1520s becomes an expression of their changing social and cultural values in the early years of the Swiss Reformation. Based on archival source materials, including foreign correspondence and city council records, this dissertion focuses on the relationship between foreign policy and domestic religious changes. Numerous political challenges faced Zurich's city council after their defeat at Marginano in 1515. The city was caught between the powerful houses of Valois in France and Habsburg in Austria. Zurich's foreign policy successfully navigated between these powers in the first half of the 1520s. Religious reform, however made it more difficult for the city to maintain the balance between these larger states. In the second half of the decade, the demand for religious unity led to mistrust of those ambassadors who had so successfully maintained Zurich's independence in European diplomacy.