We evaluate the impact on crime of a localized policing experiment that depenalized the possession of small quantities of cannabis in the London borough of Lambeth. We find that depenalization policy caused the police to reallocate effort toward nondrug crime. Despite the overall fall in crime attributable to the policy, we find that the total welfare of local residents likely fell, as measured by house prices. We shed light on what would be the impacts on crime of a citywide depenalization policy by developing and calibrating a structural model of the market for cannabis and crime.