Reducing social isolation in schools: a social network analysis of the HOPE bullying prevention program

School bullying is a public health concern, disproportionately affecting socially isolated students. Peer network position strongly influences vulnerability to victimization. This study examined the effectiveness of a Korean school-based bullying prevention program, HOPE, using social network analysis (SNA). From an initial intervention cohort of 275 students, a total of 204 students (112 boys, 92 girls) who completed both pre- and post-intervention measures across nine classrooms were included in the final analysis (attrition rate: 25.8%). In-degree centrality (IDC), defined as the number of close-friend nominations received from peers, was measured before and after the intervention as the primary outcome. SNA was conducted at baseline and post-intervention to capture changes in peer network structures. Secondary analysis examined psychosocial characteristics of students with low baseline IDC to identify factors associated with isolation and victimization. Following the HOPE program, IDC scores for previously isolated students were observed to increase. Post-intervention networks showed greater density, reflecting improved peer acceptance and social integration. Students with low baseline IDC were more likely to report elevated anxiety and lower self-esteem, underscoring their vulnerability to exclusion. Post-intervention network displayed greater density and inclusiveness with fewer students at risk of marginalization. The HOPE program was associated with enhanced social integration and promoted supportive classroom networks. By reshaping peer dynamics, the intervention may be linked to reduced isolation and strengthened protective relationships for vulnerable children. These findings underscore the utility of SNA in evaluating bullying prevention efforts and suggest that network-based approaches can provide valuable insights into how programs promote resilience and reduce bullying risk.