Background: In recent times, sibling bullying has emerged of interest to researchers
concerned with the emotional and behavioural implications for victimisation regardless
of type and setting. Aims: This research attempts to extend current knowledge on both
peer and sibling bullying and to determine the effects of poly-setting victimisation. This
paper is concerned with the following objectives: (1) determining the current rate of
bullying and victimisation among siblings and peers in a large sample of adolescents;
(2) investigating the relationship between sibling and peer bullying and depression and
behaviour; (3) highlighting the cross over effects of bullying from one setting to another
and (4) determining the overall association of poly-setting victimisation with depression
and behaviour. Sample and Methods: Over two thousand adolescents aged between
12 and 15 years participated in an online survey. Results: Results found lower rates of
sibling bullying compared to international studies. Sibling victims of bullying were at
increased risk of becoming peer victims. Poor friendship quality, disliking school, along
with peer and sibling bullying involvement predicted scores in the clinical range for
outcome measures of internalising and externalising problem. Conclusions: The
current study has clinical and educational implications for working with all important
stakeholders (i.e., schools, parents, siblings) to reduce bullying and improve mental
health.