In the international political discourse of the early 21st century, claims of friendship and “special ties” between states and their leaders are commonplace. Frequently reported by international media, such claims are often used as entry points for scholars and pundits seeking to evaluate the contents, relative strength, and present-day conditions of a given state-to-state relationship. Advancing the claim that friendships not only exist but also matter in and to the international political domain, international relations scholars began in the mid-2000s to trace and explore friendship—as a concept and practice—across time, societies, cultural contexts, and scientific disciplines. As part of the research agenda on friendship in international politics, scholars have explored why, how, and under what conditions friendships between states emerge, evolve, subsist, and dissolve; how amicable structures are typically organized; how they manifest themselves on a day-to-day basis; and what short- and long-term implications they may have for international political processes, dynamics, outcomes, and orders.