War and crises affect mental health, social attitudes, and cultural norms, which can exacerbate the state of long-term insecurity. With decades of armed conflict, the Democratic Republic of Congo is one example, and violence has become normalized in civilian settings. In this study, we tested the effectiveness of the NETfacts health system, an integrated model of evidence-based individual trauma treatment (Narrative Exposure Therapy [NET]) and a trauma-informed community-based intervention (NETfacts). Alongside changes in mental health outcomes (posttraumatic stress disorder, depression, social disapproval, and shame) we also investigated change in attitudes, including rape myth acceptance, stigmatization of survivors of sexual violence, and skepticism about the reintegration of former combatants. To test whether the additional community intervention is superior to individual NET alone, we implemented a randomized controlled design with six villages and interviewed a sample of 1,066 community members. Our results demonstrate that the NETfacts health system in comparison with NET alone more effectively reduced rape myth acceptance and with it ongoing victimization and perpetration. Community members of the NETfacts group also presented with less stigmatizing attitudes against survivors of sexual violence. Skepticism about the reintegration of former combatants declined in both groups. NETfacts appears to have increased motivation to engage in individual treatment. Synergizing the healing effects of individual and collective trauma exposure, the NETfacts health system appears to be an effective and scalable approach to correct degrading or ignominious norms and restore functioning and mental health in postconflict communities.