Teachers conceptualise and interpret violent behaviour of secondary students in different ways. They also differ in their estimates of the relevance of student and contextual school variables when explaining the severity of violence experienced by students. Research can assist here by explicating the role of different types of contextual school variables. The research question is twofold: (1) Do contextual school variables, in addition to a student's personal, family and educational variables, explain a student's violent behaviour? (2) If so, what is the role of student composition variables compared with variables indicating the social cohesion of the school? A hypothetical model was developed in which personal, family, educational and school variables of different types simultaneously explain the severity of violence experienced by a student. The method used to test the model empirically is secondary analysis of data collected in a Dutch national survey on school safety in secondary education (N students = 78,840; N schools = 219). Severity of violence experienced is assessed by the Mokken Scale on Severity of Violence Experienced (MSSVE). Multiple regression analyses reveal that a student who is older, a young male, born in the country of residence, feels at home in another country, does not have an intact family, is not religious, is enrolled in the highest educational track and is achieving lower marks in the school subjects of language and mathematics, experiences more severe violence than other students (explained variance 3.4%). Simultaneously, different types of contextual school variables are differently relevant. Mean severity of violence experienced by students at school indicates clearly more variance (2.3%) than the combination of student composition variables (0.4%). The conclusion is that the theoretical model is empirically supported, which also underlines the validity of the MSSVE. The discussion focuses on a comprehensive multilevel approach to stimulate and check improvement of social cohesion at school.