Primary care as an academic discipline and key component of the U.S. health care system faces a threatened future, despite numerous studies in the United States and cross-nationally that substantiate its health-promoting benefits. The United States remains the only Western industrialized nation that delivers primary care through three major disciplines rather than as a single specialty. This fragmented model may contribute to the fact that the United States does not have a primary-care-based health care system and that the U.S. population demonstrates poorer health outcomes than do those countries whose health systems are based on primary care and managed by a single primary care specialty. Fragmentation also creates confusion about primary care's identity, diminishes its influence because it does not speak with a common voice, and creates competition for academic and professional status, resources, curricular priority, research and training program funding, patients, and reimbursement. A large, single-specialty body of primary physicians could eliminate much duplication and competition and demonstrate greater political influence with academia, government agencies, insurers, and corporate America. A single specialty that incorporates the strengths of the three primary care disciplines would expand the clinical scope of primary care and could serve as a potent enabling force to lead health system reform. It would also produce measurable benefits for medical student and graduate medical education, health system design and service delivery, and primary care research. The author outlines a plan of action, involving all stakeholders, to initiate and achieve the single-specialty goal.