THIS ARTICLE DISCUSSES THE complexities of social and cultural diversity as demonstrated by children in a Swedish multicultural preschool setting. An integrated theoretical model which holds contemporary child and childhood theories is developed. Our particular interest is in the cultural determinants underlying diversity at a structural as well as a practice level. Results show how diversity is both defused and maintained through planned activities. The ‘social knowledge domain’ is used as a concept for describing how social interactions between children confirm and construct common clusters of social knowledge about diversity with relevance for social life at preschool.