THE UNITED STATES MEDICAL LICENSURE EXAMINATION (USMLE) program provides a single pathway for the primary licensure of graduates of Liason Committee on Medical Education (LCME)-accredited medical schools in the United States and Canada and all international medical graduates seeking postgraduate training and licensure in the United States. Graduates of accredited osteopathic medical schools may also use the USMLE to meet licensure requirements in most jurisdictions. In aggregate, the three steps of the USMLE certify that successful candidates have the minimum basic science and clinical knowledge and clinical skills for unsupervised general practice of medicine. Although the USMLE was designed to meet the needs of state licensure boards, it has significant secondary uses. These include curriculum assessment, promotion and graduation decisions, and residency selection. The USMLE program was designed in the late 1980s and was implemented in 1992, replacing the National Board of Medical Examiners (NBME) Certifying Examinations, the Federation Licensing Examination, and the Foreign Medical Graduate Examination in the Medical Sciences. There have been two major changes and additions. Computer-based testing began in 1999 (including computer-based patient management simulations) and a standardized patient-based step 2 Clinical Skills examination was added in 2004. In early 2004, recognizing changes in the academic, regulatory, and practice environment since the introduction of the USMLE, the Composite Committee that governs the USMLE directed NBME, Federation of State Medical Boards (FSMB), and Education Commision for Foreign Medical Graduates (ECFMG) staff to undertake a review of the USMLE to determine if the design, structure, and format of the program continues to support the USMLE mission in the most effective manner. The Composite Committee appointed the Committee to Evaluate the USMLE Program (CEUP), comprising 20 representatives from the broad community of USMLE stakeholders to conduct the work of the review. CEUP received information from a wide range of sources, including stakeholder surveys, open town hall sessions, and focus groups with key constituents. When it became clear that basic science educators were underrepresented in initial meetings, concerted efforts were made to gather opinions from the associations, societies, and interest groups that represent the basic science community. CEUP considered the concerns of the basic science community and incorporated them with the concerns of other stakeholders. CEUP believes strongly that the sciences fundamental to medicine form its foundation and that physicians must be thoroughly prepared to apply fundamental science to medical practice throughout their careers. Because the USMLE is a medical licensing examination, it is appropriate that, to the greatest extent possible, assessment of fundamental science principles should be undertaken in a clinically relevant context. However, CEUP recognizes that there are scientific principles and translational materials essential to medical practice that cannot be presented in this manner. The responsibility for teaching fundamental science rests with medical schools; the USMLE should emphasize the importance of fundamental science to effective clinical practice while at the same time avoiding any interference with the efforts of medical school faculty to teach fundamental science in the most effective manner. All stakeholders agree that physicians must have the ability to recognize uncertainty, gather pertinent information, and reach valid decisions …