BACKGROUND: Although the evidence-base for mental health and psychosocial support (MHPSS) interventions in humanitarian settings is growing rapidly, their mechanisms of change remain poorly understood despite the potential to improve the effectiveness and reach of interventions. OBJECTIVE: This study aimed to explore the mechanisms or factors that drive change in a modular transdiagnostic telephone-delivered mental health intervention, Common Elements Treatment Approach (t-CETA). PARTICIPANTS AND SETTING: Participants were Syrian refugee children and adolescents living in tented settlements in Lebanon. METHODS: We used a multiple n = 1 design, drawing on secondary data from 9 children who completed t-CETA during a pilot randomized controlled trial. RESULTS: Children with historical war-related trauma were more likely to show significant improvement across symptom clusters by the end of treatment compared to children presenting with depression related to daily living conditions. Children also showed fluctuating symptoms during the early stages of treatment (engagement and cognitive restructuring) but significant decline in symptoms after the trauma module (prolonged imaginal exposure) and depression module (behavioral activation). Salient external life events identified were starting or dropping out of school, working, change in living conditions, family conflict and the October Revolution
and interpersonal factors of parental engagement (with or without full attendance) and counsellor skills in building rapport were also identified as having an impact on treatment success. CONCLUSIONS: Implications of our findings are discussed in terms of integrating active ingredients into MHPSS programming, and building on parental and multi-sector involvement in child and adolescent mental health care in humanitarian settings.