Medical education reform can make an important contribution to the future health care of populations. Social accountability in medical education was defined by the World Health Organization in 1995, and an international movement for change is gathering momentum. While change can be enabled with policy levers, such as funding tied to achieving equity outcomes and systems of accreditation, medical schools and students themselves can lead the transformation agenda. An international movement for change and coalitions of medical schools with an interest in socially accountable medical education provide a "community of practice" that can drive change from within.