Abstract Background: Despite major advances in tobacco control and treatment, tobacco use remains the single largest preventable cause of morbidity and mortality in the US. Smoking prevalence is highest among Texas young adults (ages 18-29), especially those with lower education and income and those living in rural areas, like Latinos. About 19.2% of Latinos ages 18-29 in the study areas are current smokers, putting them at higher risk of cancer and other tobacco-related morbidity and mortality. Young adults are heavy users of smartphones, text messaging, social media chats, and other mobile social media, providing a remarkable opportunity for innovation in the delivery of health promotion interventions to reduce health disparities in this large and rapidly growing racial/ethnic population. This research study aims to assess the effectiveness of Quitxt, our culturally appropriate mobile smoking cessation program. Quitxt – launched by our interdisciplinary research team using proven social cognitive, motivational interviewing, and brief intervention methods for promoting behavior change – blends bilingual text and social media messaging for smoking cessation tailored to the language and culture of young adult smokers in our vulnerable region of South Texas. The team also adapted the program to the Primary Care and Mays Cancer Center patient population, and it is currently being implemented. Quitxt has not been tested in a research study, as its creation as an evidence-based cancer prevention service for young adult smokers was supported by the Cancer Prevention and Research Institute of Texas. Methods: The proposed 5-year study involves a 2-group parallel randomized controlled trial with 4 assessments (baseline, 1, 3, and 6 months) and will recruit 1,200 young adult Latino smokers: 1)The intervention group will receive Quitxt (text messaging or chat); and 2) the usual care group will receive abbreviated text messaging with health promotion-related content, including smoking cessation and referral to the Texas DSHS cessation program YesQuit. Smoking cessation will be validated via biological tests for those who report smoking cessation at the study follow-ups. We hypothesize that the group receiving the Quitxt intervention will achieve significantly higher smoking cessation rates than the group receiving usual care. Results: The proposed intervention will mark the first significant study to assess the effectiveness of an innovative, bilingual, culturally, and linguistically appropriate mobile cessation intervention tailored to young adult Latinos living in South Texas by enhancing their skills development, competence, and self-efficacy to initiate and maintain cessation. Conclusion: This study will advance public health by testing the effectiveness of a scalable, evidence-based, easily disseminated, and adaptable intervention with potentially broad national reach to help young adults stop smoking and reduce smoking-related cancer and chronic disease morbidity and mortality and their associated healthcare costs. Citation Format: Patricia Chalela, Vivian Cortez, Sandra Sivak, Armida Flores, Martha De La Mora, Zully Garcia, Byeongyeob Choi, Edgar Muñoz, Cliff Despres, Alfred L. McAlister, Qurathul Ahmed, Audrey Cordova, Maria I. Sung-Cuadrado, Luis F. Velez, Sahak Kaghyan, Rahul Mundlamuri, David Akopian, Amelie G. Ramirez. Quitxt research study: A mobile messaging intervention to promote smoking cessation among young adult smokers in South Texas [abstract]. In: Proceedings of the 17th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2024 Sep 21-24; Los Angeles, CA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2024;33(9 Suppl):Abstract nr B021.