Once children enter school, friendships and interactions with peers take on an increasingly important role in their lives. These relationships have the potential to contribute to a child’s sense of well-being and to social competence, but they are also associated with exposure to new forms of victimization. Although peer violence can take many forms, available data suggest that bullying by schoolmates is by far the most common.
 Hartup, Willard W., and Nan Stevens, ‘Friendships and Adaptation in the Life Course’, Psychological Bulletin, vol. 121, no. 3, 1997, pp. 355–370; and Rubin, Kenneth H., et al., ‘Attachment, Friendship, and Psychosocial Functioning in Early Adolescence’, Journal of Early Adolescence, vol. 24, no. 4, November 2004, pp. 326–356, available at <www.ncbi.nlm.nih.gov/pmc/articles/PMC1461415>.
- Worldwide, close to 130 million (slightly more than 1 in 3) students between the ages of 13 and 15 experience bullying.
- About 3 in 10 (17 million) young adolescents in 39 countries in Europe and North America admit to bullying others at school.
 The estimates of bullying are based on data from the Health Behaviour in School-aged Children (HBSC) and Global School-based Student Health Surveys (GSHS) conducted between 2003 and 2016. For further information on the data and methods of calculation, see United Nations Children’s Fund, A Familiar Face: Violence in the lives of children and adolescents, UNICEF, New York, 2017.