The purpose of this study was to investigate bystander behavioral intentions when adolescents witnessed cyberbullying. Self-reported data were collected from 884 junior high school students in Taiwan. The results indicated that adolescents who had negative peer relationship, higher conformity and lower levels of cognitive empathy were more likely to join in cyberbullying as perpetrators. Adolescents who had negative peer relationships, higher conformity, and lower levels of cognitive empathy were more likely to be a facilitator to reinforce or assist the cyberbullies. With positive peer relationships, lower conformity, and higher levels of cognitive empathy, adolescents were more likely to be a defender to help the victims. Outsiders were related to positive peer relationship and lower levels of cognitive empathy. In addition, girls who had higher conformity than boys would be less likely to help the victims. The implications of this research on cyberbullying are discussed.