In this chapter, I analyze the concept of ‘coalition of the willing’. The aim is not to provide a fixed definition, which contains the elements of the concept once and for all, but to explain how the concept has emerged and evolved, by whom it is used and for what purposes, and in what sense it relates with international legal and political discourses. Accordingly, the analysis is based on frame and conceptual metaphor theories as developed by George Lakoff and Mark Johnson. The preliminary conclusion is reached that 'coalition of the willing' is a conceptual metaphor according to which international cooperation is to be understood as performed by selective groups of States and other actors, which come together in a very flexible manner (i.e. informal) to efficiently pursue their goals (as opposed to classical organized multilateralism with its emphasis on inclusion and universality). Given that coalitions of the willing function on the premise of voluntary State behaviour, renouncing legal obligation, frame analysis also proves to be useful for better understanding how coalitions of the willing work, i.e. how do they induce and persuade States to perform certain conduct.