ABSTRACT The Centers for Disease Control and Prevention (CDC) recommends initiating human papillomavirus (HPV) vaccination at ages 11-12 to confer protection against anogenital and oropharyngeal cancers, though it can be started as young as age 9. Two doses by age 13 is considered “up-to-date” (UTD), i.e. protected before the onset of sexual activity. Nationally, UTD coverage was only 62% in 2021. In North Carolina (NC), a largely rural state, UTD HPV vaccination coverage is only 47% in rural adolescents. Novel approaches are needed to alleviate barriers to HPV vaccination coverage in rural areas, where adolescents may have less access to health care or a pediatrician who routinely recommends HPV vaccination. Recommending HPV vaccination at age 9 could increase UTD coverage in rural adolescents by allowing earlier completion of the series and more time to achieve UTD coverage, promoting maximal and timely HPV prevention. Achieving parity in rural HPV vaccination rates can greatly reduce urban-rural cancer disparities, including cervical cancer. The goals of the proposed K01 project are to 1) define optimal systems for recommending HPV vaccination at age 9 years in rural NC clinics; 2) assess acceptability and appropriateness of age-9 vaccination among rural caregivers; and 3) conduct a hybrid effectiveness-implementation study of age-9 HPV vaccination in rural clinics. Specific Aim 1 will collaborate with health care personnel in rural clinics to measure appropriateness and acceptability of age-9 HPV vaccination, identify opportunities for clinic-based interventions to promote it, and incorporate these insights into a preliminary intervention plan. In Specific Aim 2, we will gauge rural caregivers’ acceptability of age-9 HPV vaccination for their children, and modify the intervention plan as needed to maximize acceptability. Finally, Specific Aim 3 will pilot the intervention in four rural clinics, using electronic medical records to measure UTD HPV vaccination coverage in a cohort of 9- year-old patients over two years. My technical skills in study design and data analysis will be complemented by extensive training in clinical research and implementation science to successfully complete this project, relying on mentorship from experts in pediatric and adolescent health care, implementation science, rural health, development and evaluation of clinical interventions, and research with health care personnel. By establishing collaborative relationships with clinic research networks, understanding the key factors associated with rural health disparities, and becoming adept at developing, implementing, and measuring evidence-based interventions, my research career promises to increase vaccination behaviors in areas that are most vulnerable to infections and their consequences. In addition, I will become a well-rounded and nimble vaccine researcher, studying myriad health areas that could benefit from the introduction of novel vaccines or improved deli...