<p>Research shows that teachers’ evaluations and interactions can be influenced by students’ backgrounds, such as their ethnicity. Yet, many teachers believe that biases related to ethnicity do not exist, or that they are easy to control. Targeted interventions, which usually include evidence-based information and encourage reflection, can correct such false beliefs and reduce evaluation biases. They might be especially effective when preceded by a personalized refutation text that highlights a person’s own false beliefs. In our experimental online study, preservice and inservice teachers (<i>N</i> = 111) were randomly assigned to (a) a Stereotype Bias (SB) intervention with personalized refutation, (b) an SB intervention without personalized refutation, or (c) a control intervention. We assessed beliefs with a questionnaire and evaluations with a short task in which participants rated the performance and effort of two fictional immigrant-origin students. In contrast to the control group, the SB intervention significantly increased teachers’ beliefs that ethnicity-related biases exist and are difficult to control, with effects lasting at least 1 week. However, the SB intervention had no effect on teachers’ evaluations of immigrant-origin students. Exploratory analyses showed that the personalized refutation was particularly beneficial for teachers who initially held false beliefs. We conclude that many teachers hold false beliefs about ethnicity-related biases and that future interventions should focus on how to transfer belief change to evaluation-making. Furthermore, personalized refutation texts can enhance a person’s recognition of their own biases and thus serve as a first step toward further change.</p>