This book explores the constructivist approach in international relations as it has been developing in the larger context of social science worldwide, with younger scholars building anew on the tradition of Wittgenstein, Habermas, Luhman, Foucault, and others. The contributors include Friedrich Kratochwil, Harald Muller, Matthias Albert, Jennifer Milliken, Birgit Locher-Dodge, Elisabeth Prugl, Ben Rosamond, Nicholas Onuf, Audie Klotz, Lars Lose, and the editors.