Abstract Introduction Children exposed to trauma are vulnerable to developing posttraumatic stress disorder (PTSD) and other adverse mental health outcomes. In low-and-middle-income countries (LMICs), children are at increased risk of exposure to severe trauma and co-occurring adversities. However, relative to high income countries, there is limited evidence of the factors that predict good versus poor psychological recovery following trauma exposure in LMIC children, and the role of caregiver support in these high-adversity communities. Methods and analysis We will conduct a longitudinal, observational study of 250 children aged 8-16 years and their caregivers in South Africa, following child exposure to acute trauma. Dyads will be recruited from community hospitals following a potentially traumatic event, such as a motor vehicle accident or assault. Potential participants will be identified during their hospital visit, and if they agree, will subsequently be contacted by study researchers. Assessments will take place within 4 weeks of the traumatic event, with 3-month and 6-month follow-up assessments. Participants will provide a narrative description of the traumatic event and complete questionnaires designed to give information about social and psychological risk factors. Child PTSD symptoms will be the primary outcome, and wider trauma-related mental health (depression, anxiety, behavioral problems) will be secondary outcomes. Regression-based methods will be used to examine the association of psychosocial factors in the acute phase following trauma, including caregiver support and responding, with child PTSD and wider mental health outcomes. Ethics and dissemination Ethical approvals have been granted by Stellenbosch University and the University of Bath, with additional to recruit via hospitals and healthcare clinics being granted by the University of Cape Town, the Department of Health, and the City of Cape Town. Study findings will be disseminated via publication in journals, workshops for practitioners and policymakers, and public engagement events. Strengths and Limitations • Longitudinal methods were piloted in settlement communities of Cape Town, enabling strong links to be established with proposed recruitment sites. • Focus groups have been conducted with members of the community to ensure proposed study methods and materials are culturally sensitive. • Pilot work has demonstrated excellent retention rates, however some missing data will be expected due to study participant attrition. This will be managed using multiple imputation methods during analysis. • A limited set of biological samples will be collected, including heart rate data and dried blood spot samples. This will allow a robust examination of the biological predictors of childhood PTSD whilst maximizing study acceptability.