Indigenous peoples have historically been the butt of negative judgments and messages imposed by the dominant society. These judgments and messages reflect an absence of inclusive values, such as equity and acceptance of diversity, among the members of the dominant society. The fact that prejudiced beliefs about indigenous peoples have been upheld and passed on has contributed to the development of negative psychosocial effects and a stigmatized identity in members of such peoples. This article, set in the context of schools, seeks to identify and analyze possible expressions of ethnic prejudice among teachers in educational institutions within contexts of high social vulnerability. The methodology used is qualitative and descriptive. Focus groups and semi-structured interviews are the techniques applied. The sample is made up of 52 Chilean secondary school teachers in the Araucanía region of Chile. The sample is intentionally selected in a process is guided by the project's objectives. Data analysis employs the methodological and theoretical aspects of the Grounded Theory approach. The results show that teachers are ethnically prejudiced against indigenous students. There is a stereotyped system of beliefs widely shared by members of the teaching profession. The study reveals diverse manifestations of teachers' prejudices at the cognitive, affective and behavioural levels. Diverse prejudiced beliefs and feelings towards indigenous students are unveiled; these beliefs and feelings lead to the generation of discriminatory relational dynamics, which implicitly transmit messages of inferiority and devaluation in different forms to indigenous students. Teachers from schools in indigenous contexts are barely conscious of the prejudices with which they operate. Their practices are found to lie far from a social perspective based on acceptance of diversity in the classroom, regard for people as individuals and equity.