In this episode of In Conversation With, Ivana Nedic, Deputy Editor of The Lancet Regional Health – Europe, speaks with Sydney Tucker, Dr Susan Hillis, and Dr Tetiana Machabeli about their study evaluating Hope Groups, a group-based mental health, parenting, and violence prevention intervention for Ukrainian parents and caregivers affected by war and displacement. The conversation explores how Hope Groups were co-created in response to the needs of Ukrainian families, how the programme combines support for caregiver mental health with parenting skills and violence prevention, and what it took to conduct a cluster randomised controlled trial during an active war. The guests discuss the study’s findings, including improvements in caregiver mental health, parenting practices, and violence against children, as well as the importance of flexible, community-based delivery. The episode also examines the broader methodological and ethical challenges of conducting rigorous trials in conflict settings, including how researchers can balance scientific validity with the urgent need to provide potentially beneficial interventions and support families in crisis-affected settings.