<p>Teachers play a crucial role in addressing school bullying, yet many factors can affect their approaches. Identity-based social exclusion, where children are excluded by peers due to their stigmatised identities, is a distinct form of bullying associated with more detrimental outcomes. The social inequalities and power imbalances reflected in this type of bullying have been shown to originate from multiple levels of a socio-ecological system. This study applies a socio-ecological approach to investigate teachers’ responses to identity-based peer exclusion accounting for social identity, inequality, and diversity at teacher and school levels. Educators from UK primary and secondary school types (<i>N</i> = 303) completing an online survey were randomly allocated to an identity-based social exclusion vignette targeting different identities (i.e. ethnicity, appearance, disability, gender expression/sexuality) and asked about their responses (i.e. victim-blaming, perceived seriousness, empathy, self-efficacy, responsibility, intervention likelihood). Characteristics of teachers (gender, LGBTQ + , ethnical/cultural minority, ethnic/cultural similarity to students) and their schools (diversity, socioeconomic status, teacher training, and school support) were also assessed. Hierarchical regression analyses showed significant effects of teacher and school characteristics on teachers’ responses to the identity-based bullying. Further, a series of school-type by vignette ANOVAs revealed some differences in teachers’ responses by targeted identity as well as targeted identity by type of school interactions. The findings highlight some of the teacher and school-level characteristics that contribute to how teachers respond to different types of identity-based bullying amongst students, set against the background of a socio-ecological approach relating to social inequality and identity. Practical implications for teacher training and school-level conditions are discussed.</p>