Former child soldiers and ex-combatants are at high risk of developing trauma-related disorders and appetitive aggression, which reduce successful integration into peaceful societies. In a randomized controlled clinical trial, we offered Narrative Exposure Therapy for Forensic Offender Rehabilitation (FORNET) to 15 ex-combatants with the goal of reducing traumatic stress and appetitive aggression compared to “treatment as usual.” Measures included the PTSD Symptom Scale-Interview and the Appetitive Aggression Scale assessed prior to treatment and 2 weeks and 6 months after the treatment. We also assessed closeness to combatants as an index of reintegration. The treatment group reported reduced PTSD symptoms and less contact with combatants. Appetitive aggression decreased substantially in both groups. The results indicate that it is feasible to add psychological treatment to facilitate the reintegration process. We wish to thank the former combatants and former child soldiers who participated in this study and the Congolese translators. We also want to thank the very motivated and reliable staff of the reintegration center, especially Pascal Badibanga Zagabe, Leonce Kyakimwa, Lydie Mirimo Ajua, David Ngufu, and Matata Banyene. Furthermore, we want to thank Charlotte Salmen for conducting the follow-up interviews and James Moran for conducting the follow-up interviews as well as proofreading the manuscript. Sources of support: Deutsche Forschungsgemeinschaft (DFG), vivo international. Trial registration clinicaltrials.gov Identifier: NCT01625117