The Internet has provided a fertile ground for cyber-bullying, defined as bullying through the use of electronic media (such as computers, cell phones, and other electronic devices). Rising incidents of and tragedies from cyber-bullying have alerted researchers, educators, government officials, and parents to the severe consequence of this new form of bullying. Adopting the I3 Theory as the theoretical lens, this study aims to examine the driving and suppressing forces of bullying behavior in the cyber-space. Results from a survey of university students show that while impelling forces can increase individuals' tendency to perpetrate cyber-bullying behavior when they are instigated, inhibiting forces will represses their aggressive urge and lower their propensity to cyber-bully. Our findings not only validate the I3 Theory in the context of cyber-bullying but also provide valuable insights to educators, government officials, and parents in their effort to tackle cyber-bullying.