The basic idea of the IEA (International Association for the Evaluation of Educational Achievement) was that the educational world could be conceived as a natural laboratory. Individual countries were considered as too small and homogenous to provide explanations for differences in school performance. This perspective implied a certain way of organizing research. From its inception as a UNESCO-project in 1958, the IEA was conceived as a transnational collaborative project with researchers from different national and professional backgrounds. This paper aims at exploring the ways in which this transnational network was created and how it worked. The main focus is on the six subject survey, planned in the middle of the sixties and reported between 1973 and 1976. In contrast to the previous mathematics survey, reported in 1967, it represented a bold attempt at capturing a wide selection of school subjects (Landahl 2017; Walker 1976). The six-subject survey is interesting as an example of an early phase of international large scale assessments, where the objects and methods of the surveys were yet to be routinized. The work of IEA seems to have been characterized by a high level of creativity, and studies were seldom repeated. Instead of following a previously established template for how a study could be conducted, the wheel had to be reinvented again and again, whether it had to do about the planning, financing, construction of tests or making countries interested in participating. Drawing on IEA-documents, memories from previous members (Papanastasiou et al, 2011) of the IEA as well as correspondence of IEA:s chairman Torsten Husén, this paper tries to capture how a transnational network of educational researchers created its ideas on how and what to measure.