Constructivism is often said to simply state the obvious – that actions, interactions and perceptions shape reality. Indeed, that idea is the source of the name of this theory family. Our thoughts and actions literally construct international relations. Yet, this seemingly simple idea, when applied theoretically, has significant implications for how we can understand the world. The discipline of International Relations benefits from constructivism as it addresses issues and concepts that are neglected by mainstream theories – especially realism. Doing so, constructivists offer alternative explanations and insights for events occurring in the social world. They show, for instance, that it is not only the distribution of material power, wealth and geographical conditions that can explain state behaviour but also ideas, identities and norms. Furthermore, their focus on ideational factors shows that reality is not fixed, but rather subject to change.