The incidence of colorectal cancer has increased among younger adults (18-49 years) since the early 1990s, a well-documented trend in early-onset colorectal cancer observed in the US and worldwide. In response, the American Cancer Society in 2018 and the US Preventive Services Task Force in 2021 revised their recommendations to begin average-risk screening at age 45 years instead of age 50 years. Although initially met with skepticism, these recommendations raised important questions. How will nearly 45 million US adults newly eligible for screening be reached? Will expanding eligibility to younger adults divert resources from and compromise progress made in screening older adults? And, ultimately, what will be the effect on population-level outcomes?