School bullying cases have been increasing in number. When bullying happens, usually only the perpretator and the victim are paid attention. The bystander, the one who watches the bullying, gets less attention. The role of bystanders is crucial in the efforts of stopping bullying cases. In fact, most bystanders are unable to develop correct attitude and, therefore, unable to behave properly. This has contributed to the increasing number of bullying cases. This research aimed to investigate the role of bystanders in bullying cases at SMA 2 Sukoharjo, Central Java, Indonesia. The research applied mixed methods. The research subjects were the students of classes X, XI, and XII. The data were analysed quantitatively and qualitatively. The results of the research show that most of the bystanders, when watching an act of bullying, did not do anything to stop the bullying.