This chapter reviews key approaches to tackling bullying that have emerged since D. Olweus’ seminal work was published before exploring the way in which adopting a social identity approach to this phenomenon has helped to advance thinking even further. The sheer pervasiveness of bullying suggests that something beyond the dyadic interplay between target and perpetrator must underlie it. A social identity approach to understanding bullying is one in which all parties directly involved – perpetrators, victims and bystanders – are treated as, and perceive themselves to be, members of social groups. Moving out of the laboratory and into the classroom has shown that children’s responses to bullying vary according to what is normatively acceptable. The chapter analyses the development of bullying research since the 1970s, shifting from an initial focus on individual psychopathology towards a more social-psychological and, then, an explicitly social identity-based approach.