Abstract

School bullying remains a persistent problem with serious consequences for students’ mental health and academic development. Although bystanders are present in most bullying incidents, the psychosocial influences shaping their responses remain underexplored, particularly in non-Western cultural contexts. This study explored psychosocial influences on bystander behaviour in school bullying and identified strategies to support effective school-based interventions. Using a vignette-guided qualitative design, semi-structured interviews were conducted with 12 Chinese university students, and data were analysed using reflexive thematic analysis. Six interrelated psychosocial influences were identified as shaping bystander behaviour: (1) the emotional impact of previous bullying-related experiences, (2) self-efficacy and external support, (3) perceived responsibility within social contexts, (4) relationships and social influences, (5) perceived severity and cognitive judgements, and (6) perceived risk and self-protection. These influences interacted dynamically to facilitate or inhibit intervention decisions. While many findings aligned with existing bystander research, participants’ accounts also reflected Chinese cultural values related to harmony, hierarchy, and collective responsibility. In addition, four strategies were identified to support school bullying interventions: (1) empowering student bystanders, (2) strengthening school accountability and safeguarding, (3) enhancing teacher capacity and motivation, and (4) engaging parents through home-school collaboration. These strategies address barriers to bystander intervention across multiple contexts and highlight the importance of coordinated and culturally responsive approaches to bullying prevention. Overall, the findings highlight the need to consider psychosocial influences alongside cultural context and shared responsibility when designing effective school-based anti-bullying interventions.