The paper explores children and youths' perceptions of the reasons for bullying in multicultural schools. How do their different backgrounds explain the variations in those perceptions? The questions will be answered based on data gathered from 9 to 10, 12 to 13 and 15 to 16-year-old students (N = 2781) in Estonia, Finland and Sweden. A survey and in-depth interviews were used in the study. About half of the students have been frequently or occasionally bullied. According to the data, the reasons for bullying were frequently attributed to visible external features, such as physical appearance or clothing, but also to the bullied students' choice of friends and language use. The most vulnerable students are those with a migration background, those who speak a different language at home that is not the language of the national majority, or who have been raised in more religiously observant families.