This article demonstrates the "discovery of the social life of schoolchildren" by showing how an interest for children's peer relations emerged in a Swedish educational and medial context. Drawing on historical and sociological childhood studies, the article analyses the concept of schoolchildren's social life in the 1950s, 1960s and 1970s in relation to changes in education, society and behavioural science. At the centre of attention is the apparent shift around 1970, observable in new interests in bullying among school children, when peer relations, going from almost unnoticed, became, seemingly overnight, the centre of the Swedish media discussions of children and school. (Contains 62 footnotes.)