Objective: Two studies were conducted to (re)examine whether the strength differential hypothesis—that face-to-face bullies are likely to be physically stronger than victims—is valid in the cyberbullying domain. The novel contribution of our research includes testing the relations between the belief that strength is irrelevant for online bullying, online power (technological abilities), and cyberbullying within the theoretical integration of the Barlett and Gentile cyberbullying model and Bandura’s self-efficacy theory. Method: Two studies had participant’s complete measures of cyberbullying behavior, cyberbullying attitudes, online power, and the belief that strength is irrelevant for online bullying. Study 1 (N = 147) utilized a cross-sectional design with a general adult population, whereas Study 2 (N = 218) employed a short-term longitudinal study of college students. Results: Correlation and regression findings from Study 1 showed that (a) the belief that muscularity is irrelevant for online bullying (but not online power) was associated with more cyberbullying, and (b) this relation was mediated by cyberbullying attitudes. Study 2 replicated these results using a longitudinal path analysis. Conclusion: The current research supports the postulates of the BGCM by confirming the theoretically predicted relations between the belief that muscularity is irrelevant in the online world and cyberbullying behavior through the development of cyberbullying attitudes. Online power, in the form of computer skill, did not show this pattern, suggesting that perceptions of physical strength are more relevant even in the online world, supporting the original strength differential hypothesis. (PsycINFO Database Record (c) 2017 APA, all rights reserved)