Criminology has much to offer activities to reduce the harm of violent incidents—particularly by reducing weapon-carrying and use—but the discipline’s engagement with the harm reduction agenda has been limited. In addressing this, the article identifies risk factors for carrying a weapon by a young person in England and Wales. It demonstrates that this decision is influenced by individual-, interpersonal- and community-level factors and that weapon carriers can be distinguished from other respondents using relatively few characteristics. The study also shows that defensive factors, such as victimization and concerns about personal safety, are relevant to understanding weapon-carrying, but they are outweighed by criminogenic factors such as violence, neighbourhood disorder and, importantly, lack of trust in the police.