This study examines how the Dark Triad personality traits (narcissism, psychopathy and Machiavellianism) and school environment characteristics are associated with online and offline interpersonal violent behavior in adolescents. Online and offline violence tend to co-occur, which suggests the presence of one or more general underlying promotive/risk factors. These may be situated at the community level (e.g. the community in which the school is situated, school social capital) or at the individual level (e.g. Dark Triad personality traits, self-control, morality). Important gaps in literature include (1) the association between different types of online and offline violent behavior, as well as with online and offline victimization of these behaviors, (2) the association of Dark Triad traits and school environmental characteristics with offending and victimization of online and offline violence, (3) the role of social capital, morality and self-control in the relationship between Dark Triad traits and online/offline violence offending and victimization, and (4) the role of school social capital in the relationship between school neighborhood characteristics and online/offline violence offending and victimization. In order to fill these gaps, longitudinal data will be gathered in two waves, surveying adolescents between the age of 12 and 18 years old. Data collection will take place in secondary schools in Ghent and Antwerp and will rely on self-reports.