Trust is a core concept in International Relations (IR), representing a key ingredient in state relations. It was only relatively recently that IR scholars began to probe what trust really is, how it can be studied, and how it affects state relations. In the process three distinct ways of theorising trust in IR have emerged: trust as a rational choice calculation, as a social phenomenon or as a psychological dimension. Trust in International Relations explores trust through these different lenses using case studies to analyse the relative strengths and weaknesses of different approaches. The...