The paper addresses the recent increase in references to responsibility in global politics. It embarks from the observation that responsibility has become a key discursive element in governance realms such as security (“responsibility to protect”), economics (“corporate social responsibility”) and the environment (“common but differentiated responsibility”). While scholarship has addressed aspects of responsibility with reference to each specific governance area, the paper attempts to theorise implications that cut across the different fields. This includes a discussion of the location of moral agency; a delineation of the term from ones that are often used synonymously, such as accountability; and moral grounds of claims to responsibility.