All states require physicians and surgeons to be licensed; requirements vary by state. To qualify for a license, candidates must graduate from an accredited medical school and complete residency training in their specialty. Licensure requirements include passing standardized national exams. M.D.s take the U.S. Medical Licensing Examination (USMLE). D.O.s take the Comprehensive Osteopathic Medical Licensing Examination (COMLEX-USA). For specific state information about licensing, contact your state’s medical board. Board certification in a specialty is not required for physicians and surgeons; however, it may increase their employment opportunities. M.D.s and D.O.s seeking board certification in a specialty may spend up to 9 years in residency training; the length of time varies with the specialty. To become board certified, candidates must complete a residency program and pass a specialty certification exam from a medical certifying board. Examples of certifying boards include the American Board of Medical Specialties (ABMS), the American Osteopathic Association (AOA), and the American Board of Physician Specialties (ABPS).