This study embraced a unit-level diversity perspective to examine interpersonal aggression, as experienced or witnessed by individual team members. Specifically, our aim was to explore the moderating role of a unit’s diversity climate in the link between unit-level surface diversity in terms of ethnicity, sex, age, and tenure, and individual-level perceptions of interpersonal aggression. We tested our hypotheses with 30 nursing units using the Mixed-Linear Model procedure appropriate for nested samples. Results demonstrated that diversity climate moderated the relationships between tenure and ethnic unit diversity and interpersonal aggression, experienced or witnessed among individual team members. Moreover, regardless of the level of diversity climate, age diversity was positively linked to interpersonal aggression, whereas sex diversity was negatively linked to it. These findings imply that the unit’s context affects interpersonal aggression and provides important theoretical and practical implications to proactively prevent interpersonal aggression.