Osteopathic medical education (OME) developed during the 20th century into a separate system of training U.S. physicians. Doctors of osteopathic medicine (DOs) were educated in osteopathic medical colleges and residencies in osteopathic hospitals, took separate specialty and licensure examinations, and generally practiced in separate clinical environments from those of MDs. Founded more than 110 years ago in the United States to train osteopaths as an alternative to MD training of that time, by midcentury schools of osteopathy became schools of osteopathic medicine with the adoption of public health and biomedical principles, and osteopaths became osteopathic physicians, achieving full practice rights throughout the country. By 2000 there were 19 osteopathic medical schools, 42,000 practitioners, and a parallel system of osteopathic graduate medical education specialty training. Recently, OME’s academic and clinical training environment has changed. Heightened accreditation requirements, curriculum innovations, competency-based standards, evidence-based training, increased research on osteopathic manipulative medicine (a distinctive aspect of OME), and new and expanding colleges have occurred (nine new osteopathic campuses developed between 2000 and 2008 and a 30% increase in the first-year osteopathic medical student class). During recent decades, a movement away from osteopathic medicine’s traditionally primary-care-focused and separate training/practice system has occurred. Nearly all osteopathic hospitals closed or were integrated into allopathic hospital systems, student clinical training expanded into venues with MD education programs, fewer DO graduates pursued traditional primary care training, 60% entered training programs of the Accreditation Council for Graduate Medical Education, and DO and MD specialty practice integration became widespread. These developments have triggered a reassessment process for OME and professional organizational leadership.