This study focuses on one type of excluding and isolating behaviour, the essence of which is the breakup of social interactions with a group member, which falls within the commonly accepted definition of ostracism. Based on interviews with 29 adolescents aged 12-18 (including 15 girls and 14 boys, all of whom were students in public schools without migrant backgrounds), an analysis of the content and typology of peer ostracism in school classrooms was conducted, emphasizing the perspective of those directly involved in the ostracism, i.e., the perpetrators. Three main dimensions and behavioural aspects related to ostracism emerged from the data: "Avoidance (Zero Interaction)", "Expulsion from Group" and "Complete Ostracism". The results indicate that the identified forms of ostracism rarely occur in a pure form, and are most often carried out in combination with non-verbal acts of overt exclusion. Furthermore, peer ostracism in group-class communities, which is consensual and chronic in nature, may reflect a distinct variant that qualifies for independent study. The paper also discusses directions for future research and actions to improve the social classroom environment.