Many medical authors and organizations have called for physician advocacy as a core component of medical professionalism. Despite widespread acceptance of advocacy as a professional obligation, the concept remains problematic within the profession of medicine because it remains undefined in concept, scope, and practice. If advocacy is to be a professional imperative, then medical schools and graduate education programs must deliberately train physicians as advocates. Accrediting bodies must clearly define advocacy competencies, and all physicians must meet them at some basic level. Sustaining and fostering physician advocacy will require modest changes to both undergraduate and graduate medical education. Developing advocacy training and practice opportunities for practicing physicians will also be necessary. In this article, as first steps toward building a model for competency-based physician advocacy training and delineating physician advocacy in common practice, the authors propose a definition and, using the biographies of actual physician advocates, describe the spectrum of physician advocacy.