Bullying is a widespread social phenomenon. We show that both children who are being bullied and children who bully suffer in terms of long-term outcomes. We rely on rich survey and register-based data for children born in a region of Denmark during 1990-1992, which allows us to carefully consider possible confounders. Evidence from a number of identification strategies suggests that the relationship is causal. Besides the direct effect bullying may have on the child in the longer run, we show that an additional mechanism can arise through teacher perceptions of short-run abilities and behavior.