In this issue of JAMA Internal Medicine, Resnick and colleagues1 test the hypothesis that Medicare Accountable Care Organizations (ACOs) are associated with changes in cancer screening among beneficiaries. Accountable Care Organizations are intended to provide incentives for care coordination and promote high-quality care. In addition, measures for underuse of breast and colorectal cancer screening are routinely used to evaluate ACO quality of care. While no measures specifically address overuse of cancer screening, ACOs are responsible for downstream negative effects from overscreening—harms from the test, overdiagnosis, and overtreatment. Therefore, one would expect ACOs to increase cancer screening when appropriate and reduce cancer screening when inappropriate, reducing both underuse and overuse.