Preventing violence against women (VAW) requires witnesses to come forward, yet willingness to report is often undermined by social sanctions against those suspected of fabricating allegations. Our theory of the micro-politics of information disclosure in interdependent communities elucidates the role of social norms in preventing VAW. We present experimental evidence from a media campaign attended by over 10,000 Ugandans in 112 rural villages that featured three short videos designed to encourage reporting of VAW in the household. Results indicate a substantial reduction in VAW over a 6-month period following the campaign. Investigation of mechanisms reveals that women in the treatment group became less likely to believe that they would be labeled a gossip if they were to report an incident of VAW, and their personal willingness to speak out increased substantially. We find no evidence of a deeper change in core values pertaining to VAW.