The SPEX is a one-day, computer-administered examination consisting of eight blocks of 52 minutes each (50 questions in each block). Reflecting the fact that unrestricted licensure in the United States is for the undifferentiated practice of medicine, the SPEX measures the knowledge and cognitive abilities required of all physicians, regardless of specialty practiced.

The questions used in the SPEX focus on a core of clinical knowledge and relevant underlying basic science principles deemed necessary to form a reasonable foundation for the safe and effective practice of medicine. Content of the SPEX is intended to reflect the knowledge and cognitive abilities of practicing physicians.

The SPEX is constructed around two primary dimensions reflecting experience in medical practice: clinical encounter categories (well-care/preventive medicine; acute, circumscribed problems; ill-defined presentations or problems; chronic or progressive illness; emergency conditions, critical care; and behavioral/emotional problems) and physician tasks (data gathering; diagnostic assessment; managing therapy; and applying scientific concepts).