This paper compares the development of International Baccalaureate (IB) schools in four different settings: Argentine, Chile, Spain and Ecuador. The global comparative approach used in this study, based on actor-network theory (ANT), allows us to analyse the connections and interactions between global actors and the plurality of national, regional, municipal actors in a common conceptual frame--the IB network. The IB network includes mainly global actors, such as the Diploma Programme (DP), IB schools and the IB organisation, IB schools associations but also a myriad of local actors such as political leaders, national education administrations and local authorities. The paper examines two central assemblages: the institutional assemblage and the curricular assemblage. The institutional assemblage relates to who promotes and funds the DP in each country. While in Argentina and Chile an IB-private school assemblage prevails, in Spain it was an IB-public/private schools assemblage and in Ecuador an IB-government one. These assemblages condition the main point of passage of the IB network--the DP as a means to access to university--which further necessitates new assemblages between the DP and the official curriculum--the curricular assemblage.