Medical assistants are the fastest growing segment of primary care teams. Remarkably little is known about this emerging workforce. In this report, we present information based on a literature review, analysis of secondary workforce data, and interviews with key experts in the field that aim to highlight the basic aspects of medical assistants and discuss issues that need to be addressed in this rapidly growing occupation in the allied health workforce. Critical policy issues are raised about the future impact of a largely unregulated workforce as well as the potential impact of this field on other allied health professions.