School-based health centers (SBHCs) are a policy innovation designed to increase health care access among youth. The centers offer primary and acute care, often to underserved populations. We describe SBHCs, trace their history, and analyze the three great political challenges they face: moral opposition triggered by concern about reproductive health services in schools; funding in a managed care era; and partisan state politics. We show how the centers have been meeting these challenges. Finally, we consider the prospect of this innovation going to scale across the nation.