The current state of technology allows physicians to look up information in everyday practice using a wealth of medical resources. This change in practice may be important enough to consider it being reflected in medical certification exams, making the exam more similar to real practice. However, there is limited research comparing open- and closed-book exams in high-stakes medical certification assessments, and the research that has been conducted yields inconclusive and somewhat discrepant results. This study aims to address this gap in the literature using a large-scale controlled study in a secure testing center to determine the logistical and psychometric viability of an open-book format for all or some portion of a medical certification exam.