PROJECT SUMMARY/ABSTRACT Lung cancer remains the leading cause of cancer death, with an estimated 1.8 million deaths annually worldwide. Racial and ethnic minorities are disproportionately affected as they are more likely to be impoverished, lack insurance, and suffer disparities in treatment of lung cancer. Lung cancer screening (LCS) can reduce lung cancer mortality by 20% with close follow-up and adherence to management recommendations. Yet, how to optimize LCS adherence in a real-world population with diverse backgrounds and barriers to accessing LCS is unknown. In our recent work, we found that in a national cohort of 28,294 Veterans who underwent initial LCS, only 63% received the recommended next step in the expected time frame, with delayed or absent follow-up more likely in vulnerable populations, including Veterans who were racially Black, had mental health comorbidities, earned lower income or had higher copayments to access care. Encouragingly, Veterans who received care at high-volume LCS or academic facilities were less likely to have delayed or absent follow-up, suggesting that lessons could be learned from these LCS programs. I propose two foundational steps to enhance our understanding of the barriers to lung cancer screening and develop strategies to mitigate disparities: 1) evaluate the current structures and processes at VA facilities performing LCS designed to support equitable adherence to LCS by developing and administering surveys to these facilities and 2) conduct hierarchical multivariable regression models to identify barriers to adherence and strategies that are associated with greater in LCS follow-up overall, and among subgroups of vulnerable populations. This work represents a critical first step to identify best practices to improve adherence to LCS and ultimately mitigate lung cancer disparities among vulnerable population. This work will inform the next step in my career development, in which I will develop a tailored implementation plan and then a pilot implementation / effectiveness study in a site with a diverse population to improve mortality benefits from LCS.