The study of international organisations most often consists of an analysis of the implementation and effectiveness of their policies. This chapter takes a different approach, and discusses the processes that prevail within the International Labour Organization (ILO), upstream of the programmes it implements; it focuses on the participants who decide what the ILO does, what it cannot do and how its mandate is fulfilled. Building on the work of Robert Cox and Harold Jacobson (The Anatomy of Influence: Decision Making in International Organizations, 1973), the author will attempt to understand how this institution has developed its process of representation and decision-making since its creation. While the tripartite dynamics of the ILO and the unique role of the trade unions and employers active within it are often underlined, it will be seen that its decision-making process also responds to other logics underpinned by the political and economic balance of power (East/West, North/South, industrialised countries/developing countries), by organisational dynamics (the relative autonomy and expertise of its secretariat and director general) and by external pressures (non-governmental organisations). Based on an analysis of representation in the ILO, this chapter reveals the complexity of its decision-making process. It shows that this institution does not fundamentally upset the traditional balance of power between states, but that its influence also arises from certain structural arrangements and ways of making representation work.