Background: Evidence of 'what works' in humanitarian programming is important for addressing the disruptive consequences of conflict and forced displacement. However, collecting robust scientific evidence, and ensuring contextual relevance, is challenging. We measured the biological, psychosocial, and cognitive impacts of a structured psychosocial intervention, implemented by Mercy Corps with Syrian refugees and Jordanian host-community youth. In this paper, we present a case analysis of this evaluation study and reflect on the scientific contributions of the work, the challenges experienced in its delivery, and the strategies deployed to address them. Discussion: We identified challenges with respect to study design, methods, and dissemination: these included the logistics and acceptability of implementing a randomized controlled trial in a humanitarian context, the selection and refinement of culturally-relevant research tools and community-based practices, and the dissemination of results to multiple stakeholders. We demonstrated beneficial and sustained impacts on self-reports of insecurity, stress, and mental health; developed a reliable and culturally-relevant measure of resilience; experimentally tested cognitive skills; and showed that levels of cortisol, a biomarker of chronic stress, reduced by one third in response to intervention. Using stress biomarkers offered proof-of-concept evidence, beyond self-reported data: interventions targeting mental health and psychosocial wellbeing can regulate physiological stress in the body as well as improve self-reported mental health and wellbeing. We built constructive dialogue between local communities, scholars, humanitarian practitioners, and policy-makers. Conclusions: Our work shows the value of rigorous research in humanitarian settings, emphasizing relevance for local communities and meaningful ways to build research ownership. Findings encourage the adoption of cognitive measures and stress biomarkers alongside self-report surveys in evaluating programme impacts. High-quality scientific research with youth can be feasible, useful, and ethical in humanitarian settings.
