In the discipline of international relations, constructivism is the claim that significant aspects of international relations are historically and socially constructed, rather than inevitable consequences of human nature or other essential characteristics of world politics.
Nicholas Onuf is usually credited with coining the term "constructivism" to describe theories that stress the socially constructed character of international relations. Contemporary constructivist theory traces its roots to pioneering work not only by Onuf, but also by Richard K. Ashley, , John Ruggie, and Christian Reus-Smit. Nevertheless, Alexander Wendt is the best-known advocate of social constructivism in the field of international relations. Wendt’s 1992 article "Anarchy is What States Make of It: the Social Construction of Power Politics" published in International Organization laid the theoretical groundwork for challenging what he considered to be a flaw shared by both neorealists and neoliberal institutionalists, namely, a commitment to a (crude) form of materialism. By attempting to show that even such a core realist concept as "power politics" is socially constructed—that is, not given by nature and hence, capable of being transformed by human practice—Wendt opened the way for a generation of international relations scholars to pursue work in a wide range of issues from a constructivist perspective. Wendt further developed these ideas in his central work, Social Theory of International Politics (1999).
Since the late 1980s and early 1990s, constructivism has become one of the major schools of thought within international relations. John Ruggie and Christian Reus-Smit have identified several strands of constructivism. On the one hand, there are constructivist scholars such as Martha Finnemore, Kathryn Sikkink, Peter Katzenstein, and Alexander Wendt, whose work has been widely accepted within the mainstream IR community and has generated vibrant scholarly discussions among realists, liberals, institutionalists, and constructivists. On the other hand, there are radical constructivists who take discourse and linguistics more seriously.