As a consequence of worldwide waves of immigration there is a permanent increase of ethnically mixed school classes in countries all over the world. However, there is a lack of empirical studies on interethnic relationships which differentiate immigrant children based on their countries of origin. The present paper focuses on these topics and provides data of both negative and positive aspects of interethnic interactions. Direct and indirect forms of bullying, friendship patterns, and peer acceptance in 326 native and 242 immigrant children aged 11 to 14 (57% native Austrian, 22% former Yugoslavian, 14% Turkish/Kurdish, 7% rest group) in 29 ethnically mixed school classes (6th and 7th grades) were examined. Bullying was measured via the Olweus Bully/Victim Questionnaire and via peer nomination techniques, friendship patterns via self-ratings. Peer acceptance was defined by social preference scores on positive and negative sociometric items. According to peer ratings Austrian children were found to be more often victims (9%) and bullies (12%) of direct bullying than immigrant children. Prevalence rates in immigrant children varied depending on their country of origin between 2% and 8% for victims and 3% to 7% for bullies. Results suggested that Turkish/Kurdish children are at risk concerning their social integration in class (e.g., they had the fewest number of friends in class, reported higher levels of loneliness at school, and were less accepted by their peers compared to Austrians and former Yugoslavian children). Friendship patterns differed considerably between native children and children of the three immigrant groups. Findings are discussed concerning differences in integration strategies of immigrant children depending on their country of origin.