Developing countries host a majority of the world’s refugees, many suffering from poor mental health. Mental health in turn impacts economic preferences such as patience, risk-taking, and prosociality. These non-cognitive skills are crucial for integration, impacting educational achievement, health status and labor market success. Mental health of parents, particularly mothers, further impacts child development, contributing to the long shadow cast by war. Improving mothers’ mental health may thus have positive intergenerational effects, with long-term benefits for developing countries. Lacking resources, mental-health programs in these countries face considerable challenges. Low-cost interventions delivered by briefly trained lay facilitators offer a potential solution. Recent studies corroborate their efficacy and cost-effectiveness, but their benefits for children remain largely unexamined. To fill this gap, we implement a brief, low-cost, transdiagnostic and validated psychosocial intervention among 720 South Sudanese mothers across 24 villages in Rhino refugee camp, Uganda. We test its effectiveness in improving the mental health and non-cognitive skills of participants and their children by conducting a rigorous Randomized Controlled Trial, and gathering extensive longitudinal data. This allows us to examine in an interdisciplinary way the process of change in mental health brought about by the intervention and its impact on decision-making measured by economic games.