School bullying is a complex social phenomenon that negatively impacts the psychosocial well-being of students, as well as the overall culture and climate of schools. Designing appropriate interventions to combat bullying in South African schools requires nuanced information about this phenomenon. This paper examines the extent and nature of bullying in schools located in different and unequal socio-economic contexts. It then examines the risk factors associated with being a victim of bullying. Self-reported data from a nationally representative sample of 12,514 Grade Nine South African students, who participated in the 2015 Trends in International Mathematics and Science Study, was used. Data were subjected to analysis using independent samples t-tests and hierarchical generalised linear modelling. The results revealed different patterns of bullying victimisation and perpetration by the socio-economic status (SES) of the school, with students attending schools with a low SES reporting higher levels of bullying. Factors resulting in higher odds of being a victim were students' gender and psychosocial characteristics. Perpetration as a risk factor for victimisation (bully-victims) was found across bullying types. The results suggest that students play different participant roles as bully and victim, and that the two behaviours reinforce one another.