Diplomacy has never been a politically-neutral research field, even when it was confined to merely reconstructing the backgrounds of wars and revolutions. In the nineteenth century, diplomacy was integral to the grand narrative of the building of the modern "nation-State." This is the first overall study of diplomacy in early Renaissance Italy since Garrett Mattingly's pioneering work in 1955. It offers an innovative approach to the theme of Renaissance diplomacy, sidestepping the classic dichotomy between medieval and early modern, and reconsidering the whole diplomatic process without reducing it to the "grand narrative" of the birth of resident embassies. This volume situates and explains the growth of diplomatic activity from a series of perspectives - political and institutional, cognitive and linguistic, material and spatial - and thus offers a highly sophisticated and persuasive account of causation, change, and impact in respect of a major political and cultural form. The volume also provides the most complete account to date of how it was that specifically Italian forms of diplomacy came to play such a central role, not only in the development of international relations at the European level, but also in the spread and application of humanism and of the new modes of political thinking and political discussion associated with the generations of Machiavelli and Guicciardini.