Project Abstract This application is being submitted in response to the Notice of Special Interest (NOSI) identified as "NOT-CA- 24-041" There has been a growth in the number of cancer survivors across all age brackets, but particularly adolescent and young adults (AYAs) who experience poorer survival relative to pediatric and older cancer survivors. AYAs, even when cured from their cancer, are at an increased risk of excess morbidity and mortality, attributable to higher rates of treatment-related health conditions, including subsequent malignancies and cardiovascular disease. AYAs also have unique survivorship needs and are particularly vulnerable to gaps in care related to lack of knowledge of late effects, loss to follow up from the primary oncology team, lack of regular primary care, and the need to navigate critical transitional life milestones. Growing recognition of survivorship needs has led to the development of standardized, cancer survivor-specific screening and surveillance guidelines, with the goals of risk reduction, early detection, reduced mortality, and improved quality of life; it has also led to the establishment of National Standards for Cancer Survivorship Care. Despite the availability of these guidelines, receipt and overall quality of survivorship care is inconsistent across survivors and treating facilities, with gaps in our knowledge of survivorship care to meet the unique needs of AYAs. In response to NOT-CA-24-032, we propose a mixed methods study of AYA cancer survivors (ages 15- 39 years at diagnosis) diagnosed between 2014-2019. In aim 1, we will Identify risk factors for underutilization of survivorship care in AYA survivors and assess alignment with National Standards for Cancer Survivorship Care by linking EHR data of AYAs within our cancer registry with an online patient survey to identify what proportion of survivors have a documented survivorship visit (primary outcome) and identify risk factors and perceived barriers to receiving survivorship care across patient socio-demographics and health behaviors. In aim 2, we will conduct focus groups in a subset of AYA survivors who are high and low utilizers of survivorship care, along with key informant interviews with stakeholders in order to understand the current landscape of how national survivorship care standards are implemented, to identify factors driving under- versus high utilization of AYA survivorship care, and to develop priorities for enhanced survivorship care that directly address patient-driven approaches for reducing barriers. The results of the proposed research have the potential to inform strategies to optimize AYA survivorship care and its utilization, to identify demographic and geographic utilization differences, and to inform future survivorship care interventions that promote high- quality, equitable, and sustainable use of survivorship care among AYA cancer survivors.