Abstract: The objectives of this study are to examine colorectal cancer (CRC) screening, incidence, and mortality among veterans 45 to 75 years who are enrolled in the U.S. Department of Veterans Affairs (VA) healthcare system by housing instability or homelessness (HUH) and determine whether receiving primary care via Homeless Patient Aligned Care Teams (HPACTs) affects CRC screening, incidence, and mortality among veterans experiencing HUH. A retrospective cohort study was conducted among > 3,000,000 veterans who sought VA healthcare services (1 January 2019 to 31 December 2021) using three linked VA databases (Corporate Data Warehouse, Homeless Operations Management System, and Department of Defense/VA Joint Mortality Data Repository). Multivariable regression models were constructed to estimate odds ratios (OR) and hazard ratios (HR) with their 95% confidence intervals (CI). In fully adjusted models, HUH was associated with lower odds of CRC screening (OR = 0.68; 95% CI, 0.67-0.69), but a higher risk of CRC diagnosis (HR = 1.12; 95% CI, 1.03-1.22) and CRC-specific mortality (HR = 1.50; 95% CI, 1.04-2.16). Among veterans experiencing HUH, those enrolled in HPACTs were as likely as those not enrolled in HPACTs to undergo CRC screening or be diagnosed with CRC. These findings suggest HUH may be detrimental to CRC screening, diagnosis, and prognosis among veterans. Evidence-based interventions within HPACTs may help promote CRC screening, thereby reducing CRC morbidity and mortality risks among aging veterans with histories of HUH.