Background: Nearly one-third of all colonoscopies are performed for surveillance (i.e., follow-up) of previously identified colorectal neoplasia. Despite existing evidence-based guidelines for colorectal neoplasia surveillance, data show overuse of surveillance colonoscopy for low-risk and underuse for high-risk colorectal neoplasia, even in integrated health systems such as the Veterans Health Administration (VHA). Overuse of surveillance for low-risk neoplasia leads to exposure to unnecessary harms, wastes limited resources, and creates barriers to access. Underuse of surveillance for high-risk neoplasia leads to increased risk for future colorectal cancer (CRC). There is a critical need to address the imbalance of surveillance to optimize allocation of limited colonoscopy resources in the VHA. Little is known about factors related to under- and overuse of surveillance in this setting. Efforts to develop targeted interventions that address both underuse for high-risk Veterans (who benefit most from surveillance) and overuse for low-risk Veterans (who benefit little or not at all) are needed as the demand for colonoscopy far exceeds the capacity in the VHA. Significance/Impact: Current efforts to improve access to colonoscopy resources are primarily focused on shifting screening to non-invasive, stool-based tests. The overarching goal of this proposal is to develop and pilot test an intervention to optimize surveillance by improving access to, and efficiency of, this costly and limited resource at the VHA. Through this work, we seek to ensure delivery of high-quality, equitable, and timely patient-centered care. Innovation: Existing guidelines for surveillance intervals by themselves are not effective in the real-world. The proposed work will shift the current paradigm for optimizing colorectal neoplasia surveillance by studying and addressing factors at the patient-, provider-, and system-levels to identify targets for intervention. Cross-cutting methods, using a theory-based, structured approach, will be used by an interdisciplinary team of experts to improve colonoscopy resource use and access in the VHA. Specific Aims: We will first characterize patient-, provider-, and facility-level factors associated with colorectal neoplasia surveillance adherence and non-adherence (Aim 1). We will then conduct a formative evaluation of barriers and facilitators from the perspectives of patients, providers, and staff to design an intervention that optimizes surveillance use (Aim 2). And finally, we will pilot test the intervention to determine feasibility and acceptability (Aim 3). Methodology: In Aim 1, we will use national VHA data to identify Veterans who are between the ages of 50 and 75 years and have had either low- or high-risk colorectal neoplasia on their colonoscopies. We will then characterize patient-, provider-, and system level factors associated with surveillance adherence and non- adherence using a multilevel mixed-effects logistic regres...