Objectives: The aim of this study is to investigate the association between ethnic composition in school and the ethnic prejudice of teachers, controlling for the individual characteristics of teachers and their perceptions of pupils’ teachability. Method: Multilevel analyses were carried out on data for 499 Flemish teachers in 44 Flemish (Belgian) secondary schools, collected through an online questionnaire. In this study, ethnic prejudice means a negative attitude to Moroccans, Turks, and Eastern Europeans. A scale was created by taking the mean scores for 18 items, with higher scores indicating greater ethnic prejudice (Quillian, 1995; Witte, 1999). Results: Teachers with long-term higher education or a university diploma are shown to be less ethnically prejudiced than teachers with a lower level of education. Moreover, teachers who work at a school with a greater number of ethnic minority pupils, and at the same time evaluate their pupils as more teachable, are less ethnically prejudiced. Conclusions: These findings highlight the need for more research into the underlying processes, such as pupils’ teachability, that influence the relationship between school characteristics and the ethnic prejudice of teachers. More knowledge about the context-specific factors and processes that mediate and/or moderate this relationship can increase the theoretical understanding of the development of ethnic prejudice. It can also highlight particular social characteristics, which can be the focus of social and organizational policy aimed at reducing ethnic prejudices.