This paper offers a conceptualization and operationalization of the professional knowledge of future middle school teachers for teaching English as a foreign language (TEFL), whom the authors directly assessed using tests developed by the research group. The authors conclude that test score differences by phase and program as shown in this study are well aligned to certain priorities laid down in the initial teacher education curriculum. The authors consider this as evidence for the curricular validity of the tests. The authors suggest that the tests could be used to inform about learning progress of student teachers throughout their teacher preparation program.