Guidelines for cancer screening written by different organizations often differ, even when they are based on the same evidence. Those dissimilarities can create confusion among health care professionals, the general public, and policy makers. The Institute of Medicine (IOM) recently released 2 reports to establish new standards for developing more trustworthy clinical practice guidelines and conducting systematic evidence reviews that serve as their basis. Because the American Cancer Society (ACS) is an important source of guidance about cancer screening for both health care practitioners and the general public, it has revised its methods to create a more transparent, consistent, and rigorous process for developing and communicating guidelines. The new ACS methods align with the IOM principles for trustworthy clinical guideline development by creating a single generalist group for writing the guidelines, commissioning independent systematic evidence reviews, and clearly articulating the benefits, limitations, and harms associated with a screening test. This new process should ensure that ACS cancer screening guidelines will continue to be a trustworthy source of information for both health care practitioners and the general public to guide clinical practice, personal choice, and public policy about cancer screening.