Students with Turkish or Arab migrant background are disadvantaged in terms of educational outcomes (e.g., school achievement) in different domains in the German education system. In addition, studies have documented that teachers hold negative (performance-related) stereotypes towards these students. The proposed research project seeks to examine an additional mechanism that unfolds and potentially harms the classroom engagement and participation of students with Turkish or Arab migrant background: teachers' reactions to students' disruptive behavior in the classroom. The present research suggests a new, context-based discrimination model that proposes that teachers' reactions to students' disruptive behavior in the classroom are affected by processes unfolding at the micro level (i.e., social categorization; stereotyping), the immediate context level (i.e., classroom composition), and the intermediate context level (i.e., neighborhood composition). More specifically, the suggested model argues that the ethnic composition of school classes affects teachers’ (a) chronic activation of stigmatized students’ ethnic group membership; (b) activation and application of stereotypes associated with stigmatized ethnic groups; and (c) their decision-making in the classroom regarding the propensity to use disciplinary measures (i.e., context-based discrimination). Additionally, the ethnic and socioeconomic composition of the geographic areas surrounding schools (e.g., catchment areas) likely moderate context-based stereotyping and discrimination at the classroom level. The proposed project aims at establishing the validity of the model by examining the effects of ethnic classroom composition on stereotyping and decisions to use disciplinary measures among German pre-service (Study 1) and in-service teachers (Study 2), using an experimental between-participants design.