The sharing economy has fundamentally transformed customers’ lives. Providing short-term access to resources, however, creates environments in which customers regularly become the target of other customers’ misbehavior, either personally or toward shared resources. Although this customer-to-customer (C2C) misbehavior is known to be contagious, the reasons for its spread and the effectiveness of containment measures across sharing economy markets remain unclear. Three experiments reveal the moderating role of on-site supervision: platform-provider-directed blame attributions drive C2C misbehavior contagion in settings with formal on-site supervision, while social norms underlie contagion when on-site supervision is absent. Perpetrator-directed blame attributions reverse contagion irrespective of on-site supervision. More intrusive platform and peer-provider measures (in-person reprimands, in-app messages, and photo features) are most effective at curbing contagion by reducing social norms to misbehave and shifting blame to the perpetrator. However, these measures are only effective at certain C2C misbehavior severity levels for different sharing economy market types.