This chapter aims to complement the research on the effectivity of international Trusteeship with a perspective on its affectivity. Following the recent discussion of social and cultural theory of affect, the Trusteeship System is conceived as an affective arrangement. The chapter develops the argument that the Trusteeship System is not only based on the principles of rational-legal rule but is also constituted by a variety of affective relations and affective practices that have hardly been considered so far. In applying affect theory to the analysis of Trusteeship, the chapter aims at, first, showing that Trusteeship can be understood as a situated affective arrangement of people and objects. Second, the article explores the diversity of affective practices within the Trusteeship System. In this way, third, the chapter contributes to a broader understanding of international bureaucracy and international rule by arguing that international administration, although it is based on rational-legal administrative practices, includes an inescapable affective dimension. Thus, it is argued that the Trusteeship System is based not only on international treaties and the bureaucratic procedures of the involved administrations of both the United Nations and the mandated powers but also on affective ties and the mobilization of affects in the relations among international actors, trustees and the populations in the administered territories.