Despite the growing body of evidence that the origins of bullying lie in early childhood, very little is known about the nature of the phenomenon in preschool groups. The current understanding among studies conducted in the school environment is that bullying prevention can only be effective if training with individual children takes place parallel to broader interventions in the classroom. The aim of this study was to examine how bullying prevention should be focused among under school-aged children. Since we know that children with special educational needs (SEN) have been found to be extremely vulnerable to bullying and victimization, we examined the role of three- to six-year olds with SEN in bullying situations. In addition, we examined whether the peripheral roles of other children in bullying situations can already be observed in preschool groups. The data were collected from a survey of day care staff in the city of Vantaa (n = 771). According to staff reports, 18% of bullying took place in situations in which children with SEN were present. Bullies with SEN used more physical forms of bullying and bullies without SEN used more psychological forms of bullying. The findings also showed that the multiple, peripheral roles of the bystanders in bullying situations are already occurring in preschool groups, especially among boys. It is important to target intervention programs in preschools both on individual children and at group level. (author abstract)