Evidence shows that lead-exposed children are more disruptive and have lower achievement. However, we know less about how lead-exposed children affect the learning environment of their classroom peers. We estimate these spillover effects using new data on children's blood lead levels (BLLs) matched to all education data in North Carolina. We compare siblings who attend the same school, but whose school-grade cohorts differ in the proportion of children with elevated BLLs. We find that having more lead-exposed peers is associated with lower test scores and graduation rates, increased suspensions and dropping out of school, and a decrease in college intentions.