Clarification of how individuals in different roles perceive the victims and causes of bullying is of great importance to educational research and practice. The present study aimed to investigate the opinions of individuals in different roles (bullies, victims, bystanders, educators) regarding the targets and causes of bullying and to identify differences among various perspectives. A total of 1558 participants from 77 secondary schools in Taiwan responded to the questionnaire, including 537 bystanders, 217 bullies, 213 victims, and 591 educators. Grounded-theory method was employed to analyse the qualitative data. A theoretical model addressing commonalities among the perspectives held by individuals in different roles suggested that at-risk targets, including provocative, vulnerable, and atypical students, had poor interpersonal relationships. The bullies selected their targets based on different motivations, which included having fun, releasing emotions, and achieving status or benefits. The research found differences between the perspectives of educators and those of student participants regarding the causes of school bullying with respect to blaming victims, the intentions of bullies, intolerance of diversity in peer cultures, and the influence of contextual factors. Increasing awareness and minimizing these differences may help efforts to prevent and intervene in bullying.