To date, no theory of bullying in residential care for youth has been proposed. By drawing on the results of the existing research on bullying and peer violence in youth residential care and adapting the Multifactor Model of Bullying in Secure Settings (MMBSS), this paper proposes the first integrative theory of bullying in residential care-the Multifactor Model of Bullying in Residential Settings (MMB-RS). The paper first summarises the existing empirical findings on bullying and peer violence in residential care for youth and describes the MMBSS. It then moves on to proposing and describing the MMB-RS. In a nutshell, the MMB-RS assumes that bullying in residential care is shaped by a dynamic interaction between a complex set of individual and contextual factors. The model also takes into account the interaction between bullies and victims, thus explicitly considering the social interactional components of bullying and victimisation and offering possible explanations of the sizable overlap between bullying and victimisation in residential care, including the possible contributions of residential peer cultures. The paper concludes by noting the importance of empirically testing the MMB-RS and proposing a programme of research that may be helpful in testing it.