The Yearbook of Transnational History is an annual series dedicated to disseminating pioneering research in the field of transnational history. The ninth volume of The Yearbook of Transnational History brings together six case studies that interrogate the idea of a "special relationship" in international affairs, asking what makes certain bilateral ties stand out, how they are sustained, and whether their distinctiveness rests on sentiment, strategic calculation, or a combination of both. Moving across regions, historical periods, and thematic focuses, the chapters explore whether the term "special relationship" reflects a genuinely exceptional bond or operates as a flexible diplomatic idiom and reveal how such relationships can be forged through high politics, personal diplomacy, cultural exchange, and even covert cooperation. Together, they show that "specialness" is rarely a fixed attribute; it is constructed, performed, and renegotiated over time in response to changing political contexts and mutual needs