Despite growing research on nonsuicidal self-injury (NSSI) in university settings and evidence that the risk of engaging in NSSI increases when they know someone who does, little is known about the relationship between social exposure to NSSI and students' perceptions of public stigma regarding NSSI. Drawing on intergroup contact theory, which posits that increased contact with stigmatized groups reduces prejudice, understanding how knowing someone who self-injures relates to stigma is particularly important. This study addressed these gaps by examining these factors among university students from three countries. Potential commonalities across countries and the moderating role of personal NSSI history were also examined. A total of 1,059 students (77.4% female, M-age = 21, age range = 17-53 years) participated, having been recruited on the basis that they knew someone who engaged in NSSI. Participants (50.8% Australian, 33.4% Belgian, 15.8% Canadian) completed a survey reporting on their own experiences with NSSI, the perceived NSSI experiences of the person they know who self-injures, and perceptions of public attitudes and stigma toward NSSI. Participants most commonly identified friends as the individuals they knew who self-injured. Pearson's correlations revealed positive interrelations among social exposure to NSSI and perceived public NSSI stigma. Hierarchical regression and moderation analysis showed this association was moderated by country, but not by personal NSSI history. Analysis of variance results indicated Canadian students perceived significantly lower levels of public NSSI stigma compared to Australian and Belgian counterparts. These findings underscore the importance of implementing stigma-reduction strategies sensitive to country-specific contextual factors. Future research should further explore the role of knowing someone who self-injures, as well as cultural and national influences on stigma perceptions.