Children exposed to Interparental Verbal Conflict (IPVC) exert negative spillovers on their peers. Using nationally representative survey data from middle schools in China, focusing on schools that randomly assign students into classrooms, and using both (1) within-school, across-classroom variation and (2) within-student, year-to-year variation to identify effects, we find that being assigned to classes where more classmates experience IPVC reduces mental wellbeing, diminishes self-confidence, lowers social engagement, and increases the likelihood of problem behaviors. Effects operate by damaging relationships between classmates. There is no evidence of impacts on test scores or teacher's outcomes.