Ethiopia has made substantial progress in improving health outcomes during the last decade and is on track to achieve some of the health Millennium Development Goals. Innovative strategies to improve household behaviors and coverage of basic health care services contributed to Ethiopia's achievements, and the Health Extension Program (HEP) remains the core of such innovations and provides a model for countries struggling to improve health outcomes in a resource-constrained setting. The program rests on an accelerated expansion of basic health infrastructure and local human resources with required skills to scale-up delivery of high-impact interventions focusing on improving the supply of and enhancing demand for a well-defined package of essential promotive, preventive, and curative health services. The objectives of the case study are to provide a detailed description of (a) the context for the introduction of the program; (b) the scope of the service package delivered under the program; and (c) the institutional arrangements and the links with the rest of the health system. The case study also summarizes and discusses the evidence of the program's achievements and the challenges to achieving universal primary health care coverage. The study also discusses the importance of political will and commitment in introducing such large-scale innovations in improving service delivery and mobilizing the community in a resource-constrained setting.