Three national guideline groups now recommend that all adults start colorectal cancer (CRC) screening at age 45. Before 2018, some guideline groups only recommended African Americans begin CRC screening at age 45. There is currently no empirical evidence of the value of screening before age 50. The only evidence comes from modeling studies and observational data collected in cancer registries, such as SEER. This project will evaluate the acceptance, uptake, and yield of mailed FIT screening among KP members in Northern California, Southern California, Washington, and Colorado. The findings will help National Guideline Directors make a recommendation to the Permanente Medical Groups and the Kaiser Foundation Health Plan about starting CRC screening at age 45.