There has been a call for cross-cultural research in the understanding of non-suicidal self-injury (NSSI). The purpose of this study was to explore the influence of ethnicity and culture on the understanding of NSSI among social work students in the United States, Greece/Cyprus, and Jordan. A convenience sample of 438 social work students was used. Participants completed a 60-item questionnaire. Results revealed statistically significant differences in students’ knowledge and cultural beliefs about NSSI by country. This study makes a novel contribution to the exploration of cultural aspects of NSSI and has implications for international social work practice and education.