The present study examines why some studies of the Proteus effect—the phenomenon that people tend to conform behaviorally and attitudinally to their avatars’ identity characteristics—facilitate the phenomenon more effectively than others. A previous meta-analysis of the Proteus effect (Ratan et al., 2020 ) failed to examine potentially notable moderating factors of the phenomenon, so we examine such factors through a meta-analysis of the 56 quantitative experimental Proteus effect studies published at the time of this analysis. Studies that utilized virtual reality technology (e.g., head-mounted displays) elicited stronger effect sizes than those that utilized flat screens, as hypothesized. No support was found for the hypothesis that effect sizes differ by software type utilized (commercial or custom-built). We offer suggestions for future research into the Proteus effect, and how to best examine possible variables of the phenomenon.