In this research, prototypicality of the aggressor will be tested as a group-level contextual factor predicting social media users’ active participation to cyberaggression. In a series of experimental studies, participants will be exposed to a fictitious conversation, in which either a highly prototypical or a low prototypical user has posted an aggressive comment as a reply to a provocative comment. We hypothesize that bystanders (our participants) will post an aggressive comment and rate the aggression as acceptable more in the highly prototypical than in the low prototypical condition.