ABSTRACT Socioecological models of bystander intervention suggest that a complex decision-making process is required for a prosocial bystander to intervene, starting with intrapersonal variables of cognition and personality. This study investigates how rape myth acceptance, personality, and just world beliefs impact the frequency of positive bystander intention. The study’s sample size consisted of 139 college students. Participants completed an online survey in which they read a vignette and indicated whether they would intervene as a bystander at 25 different instances throughout the vignette. Correlational analyses showed that agreeableness and openness were positively associated with prosocial bystander behavioral intention. A multiple regression analysis found only the belief that the world was a safe and good place was predictive of prosocial bystander behavioral intention. The results suggest that bystander intervention education programs should be revised to address just world beliefs.