The aim of this study was to investigate how individuals;who had been victims of school bullying; perceived their bullying experiences and how these had affected them; and to generate a grounded theory of being a victim of bullying at school. Twenty-one individuals, who all had prior experiences of being bullied in school for more than one year, were interviewed. Qualitative analysis of data was performed by methods from grounded theory. The research identified a basic process of victimising in school bullying, which consisted of four phases: (a) initial attacks; (b) double victimising; (c) bullying exit; and (d) after-effects of bullying. Double victimising refers to a process in which there was an interplay between external victimising and internal victimising. Acts of harassment were repeatedly directed at the victims from their social environment at school -- a social process that constructed and repeatedly confirmed their victim role in the class or the group. This external victimising affected the victims and initiated an internal victimising; which meant that they internalised the socially constructed victim-image and acted upon this image, which in turn often supported the bullies' agenda and confirmed the socially constructed victim-image. The findings also indicate the possible positive effect of changing the social environment.