This thesis seeks to establish the concept of jurisdiction as an analytical framework for conceptualising the powers of international organizations. The basic claim is that a distinction ought to be drawn between the types of actions an organization can take and the legal relationship between the organization and the persons, objects and scenarios where it is empowered to act. Existing scholarship focuses solely on the former dimension whereas the latter, referred to as jurisdiction, is underexplored. The thesis develops an analytical framework comprised of elements which are essential components of international jurisdiction. This framework is derived from the reasoning of the PCIJ and the ICJ on international organizations. It identifies three foundational elements which are essential and incommensurable: state consent, techniques of delimiting jurisdiction and the compétence de la compétence principle. The framework seeks to examine each of these elements individually, but also to capture the dynamic between them. It is not claimed that the distinction between the types of action and the relationship between institution and objects; between jurisdiction and legal powers, is always watertight. However, it is argued that reconceptualising the ‘powers’ of organizations along the lines advanced by this thesis is beneficial in two ways. First, it is argued that the introduction of the concept into existing constructions concerning legal powers adds nuance and subtlety, therefore enhancing the ability of law to act as an effective constraint upon international organizations. Second, the concept of jurisdiction offers fresh insights into complex questions of contemporary global governance, in particular, the overlapping competences of organizations. Advisors/Committee Members: SCOBBIE, IAIN I, D'Aspremont, Jean, Scobbie, Iain.