PROJECT SUMMARY Non-Communicable Diseases (NCDs) are the leading cause of global mortality, constituting 70% of deaths worldwide, 80% of which occur in Low- and Middle-Income Countries (LMICs). Tobacco use, a leading risk factor for NCDs, is responsible for 8 million deaths annually. Among all regions of the world, Africa has the highest predicted increase in tobacco use by 2025 (37%), even as use in the Americas is expected to decrease by 54%. Interventions are needed to address the explosion in tobacco use in Africa and other LMICs and to avert global deaths from tobacco. Emergency Department (ED) populations are a high-risk group that are opportune for interventions targeting NCDs and NCD risk factors, like tobacco. However, research in ED populations in LMICs is limited. Our team has led research in African ED populations, including conducting the largest epidemiological study on NCDs, and demonstrated that the burden of NCDs and NCD risk factors, such as tobacco, are systematically worse in ED populations than the general population. Mobile health (mHealth) interventions have had demonstrated effectiveness for tobacco cessation in High-Income Countries and for ED-based mHealth interventions in the US as shown by our team and others. mHealth interventions have been used in Africa to target communicable diseases such as HIV and tuberculosis, however there have been no trials assessing effectiveness for NCDs. This represents a substantial missed opportunity: mHealth is ideal for African settings because it can circumvent limited human resources, disseminate information to large populations, and do so at minimal cost. Our team has developed Text2Quit, a novel text message-based mHealth tool addressing tobacco cessation in the US. The program has shown a doubling of biochemically confirmed smoking cessation in US populations, and has been adapted in two international settings. In this study, we hypothesize that adapting and implementing Text2Quit in a Kenyan ED population will increase knowledge and cessation. We plan to use a mixed-methods, hybrid implementation-effectiveness approach to assess these outcomes. Our results will inform a randomized, controlled trial in a nationally representative sample of EDs in future. This study will be the first to target tobacco use in this population, the first to use mobile cessation, and will contribute to advancing implementation science on tobacco cessation globally. It will also provide a novel approach to implementation for mHealth interventions, with findings that can be generalized to other NCDs and risk factors, such as alcohol use, hypertension and diabetes. Our team, which includes the creators of Text2Quit, experts in implementation science, and mixed methods researchers with more than two decades of experience in ED populations, mHealth and NCDs in Africa, is well poised to conduct this study.