A 2008 policy change by the Centers for Medicare and Medicaid Services (CMS) eliminated reimbursement for certain preventable errors, including selected never events and hospital-acquired infections. The impact of the policy was debated, including the ability of providers and systems to accurately identify conditions present on admission. This study involved an educational intervention to assess the policy's impact on clinical practice among trainees. In a series of presented clinical vignettes, members of the intervention group, who received education about the new policy as part of the study, were less likely than participants who received no such education to select the most clinically appropriate response. While all the trainees acknowledged responsibility to understand CMS documentation rules and felt poorly trained to do so, their responses to the vignettes raised concern about the potential harm and unintended consequences caused by unnecessary testing and procedures that may result from the policy. The implications of the CMS policy are further discussed in an AHRQ WebM&M perspective.