Over 40-years of research has highlighted the prevalence of peer victimisation, and the impact experiencing this behaviour can have on adolescents’ mental health. Underpinned by the transactional model of stress (Lazarus & Folkman, 1984) and the socio-ecological model (Bronfenbrenner, 1979; Espelage & Swearer, 2003), the aim of this thesis was to examine the role of cognitive appraisals in the relationship between peer-victimisation and poor mental health. Three studies were undertaken: a systematic review of extant literature; the secondary data analysis of a cross-sectional study of 3,737 pupils examining the role of domain-specific perceived social support in the relationship between bullying, cyberbullying and poor mental health; and a longitudinal study of 530 adolescents aged 11 to 14 examining the role of cognitive appraisals in the relationship between peer-victimisation and symptomatology. The results of the systematic review highlighted an inconsistent pattern of findings regarding the role of perceived social support. Both the cross sectional and longitudinal study found that perceived social support from parents/guardians, teachers, and friends did not significantly moderate the relationship between peer-victimisation and poor mental health. The results of the systematic review also highlighted a role for threat and control cognitive appraisals in this relationship. Cognitive appraisals of threat, challenge, control and blame were examined in the longitudinal study. Results of this study found a small but significant total indirect effect for threat and challenge appraisals in the development of depressive symptomatology. This study is the first to report a role for challenge appraisals in adolescents’ adaptations to peer-victimisation. The findings of this thesis highlight the utility of the transactional model of stress and socio-ecological model for researching the relationship between peer-victimisation and poor mental health.Over 40-years of research has highlighted the prevalence of peer victimisation, and the impact experiencing this behaviour can have on adolescents’ mental health. Underpinned by the transactional model of stress (Lazarus & Folkman, 1984) and the socio-ecological model (Bronfenbrenner, 1979; Espelage & Swearer, 2003), the aim of this thesis was to examine the role of cognitive appraisals in the relationship between peer-victimisation and poor mental health. Three studies were undertaken: a systematic review of extant literature; the secondary data analysis of a cross-sectional study of 3,737 pupils examining the role of domain-specific perceived social support in the relationship between bullying, cyberbullying and poor mental health; and a longitudinal study of 530 adolescents aged 11 to 14 examining the role of cognitive appraisals in the relationship between peer-victimisation and symptomatology. The results of the systematic review highlighted an inconsistent pattern of findings regarding the role of perceived social support. Both the cross sectional and longitudinal study found that perceived social support from parents/guardians, teachers, and friends did not significantly moderate the relationship between peer-victimisation and poor mental health. The results of the systematic review also highlighted a role for threat and control cognitive appraisals in this relationship. Cognitive appraisals of threat, challenge, control and blame were examined in the longitudinal study. Results of this study found a small but significant total indirect effect for threat and challenge appraisals in the development of depressive symptomatology. This study is the first to report a role for challenge appraisals in adolescents’ adaptations to peer-victimisation. The findings of this thesis highlight the utility of the transactional model of stress and socio-ecological model for researching the relationship between peer-victimisation and poor mental health
