Early modern Europe witnessed profound changes in the institutions, conduct, and personnel of diplomatic relations between polities. In general, there was a shift to diplomacy becoming a constant, regular activity of the state, and, bureaucracies, protocols, and archives related to the conduct of diplomacy emerged across Europe. While it was far from universal, the exchange of resident ambassadors, attached to foreign courts and governments more or less permanently, became a regular feature in European statecraft. Many diplomatic exchanges remained ad hoc, carried out by extraordinary envoys, and asymmetric diplomacy was still common into the 17th century. Although genuine professionalism in diplomatic service was hard to detect, by the end of the 17th century the major European states had developed secretariats of state and foreign ministries, sectors of government dedicated to the prosecution of overseas affairs. A genuine “culture of diplomacy” was in place. This view of an emerging modern European diplomacy was shaped, and largely remains so, by a seminal work from the mid-20th century, Garret Mattingly’s Renaissance Diplomacy, first published in 1955. While Mattingly did not evince a comprehensively Burckhardtian break between the Middle Ages and Renaissance, he did locate the origins of modern diplomacy in 15th century Italy, with the use of residency by Italian territorial states. He saw the Habsburgs as the chief heirs to the Italian diplomatic system in the 16th century, with a Europe-wide model based on the principle of balance of power in place after the Treaty of Westphalia (1648). The bibliography that follows reflects the deep and abiding influence of Mattingly’s state-centered model, but also the many innovations and departures associated with the “new diplomatic history.” This recent work has embraced a more expansive understanding of what constitutes diplomacy, who qualifies as a diplomatic agent, how diplomatic sources should be interpreted, and what facets of diplomatic exchanges are worthy of study. In so doing it has complicated and refined Mattingly’s vision. Several of the sections below concern specific historiographical thrusts of the new diplomatic history. The best work in early modern diplomatic history, however, remains rooted in the extraordinary richness of its source material, especially the millions of pages of correspondence that provide a real-time window into the early modern world. Vincent Ilardi, who did so much to bring attention to the enormous promise of examining Renaissance Italian diplomatic correspondence, once wrote, paraphrasing Braudel and with tongue wedged only half in cheek, that Renaissance diplomatic history might in fact offer a sort of histoire totale. There is something in it for everyone.