Previous research shows that ethnic minority students perform poorer in school when they are taught by teachers belonging to the ethnic majority. Why this is the case was unclear. This paper focuses on one important potential explanation: I examine whether ethnic majority teachers grade minority and majority students differently for the same work. Using an experiment, I show that such a direct grading bias does not occur. I do find indirect evidence for alternative explanations: teachers report lower expectations and unfavorable attitudes that both likely affect their behavior towards minority students, potentially inducing them to perform below their ability level. Effects of having ethnic majority teachers on minority students' grades hence seem more likely to be indirect than direct. © 2011 Elsevier Ltd.