OECD and IEA International Large-Scale Assessments (ILSAs) contractors have remained largely invisible despite playing a key role in the making of education assessment data. With the help of Bourdieu’s thinking, this paper analyses data generated through document analysis of ILSA Reports and in-depth interviews with staff working on ILSAs at the IEA, the OECD and ILSA contractors. The paper traces education assessment developments in the USA and at the IEA and the OECD since the 1980s, and points to the critical role of Education Testing Services (ETS). Although the selection of ILSA contractors ostensibly occurs through a globally competitive tendering process, this paper reveals the pressures and struggles that emerged when economic capital became available at the IEA and the OECD. The struggles reveal PISA was created as a competing project to TIMSS. The paper demonstrates how the social and cultural capitals that individuals acquired, and in particular trust, shaped who can and who cannot produce ILSA data today. Overall, the paper makes visible the ILSA data chefs and their recipes: ILSAs are not raw, they are cooked under pressure with personal and organizational tensions, struggles, conflicts, and emotional bonds.