The World Health Report 2000 is an expert analysis of the increasingly important influence of health systems in the daily lives of people worldwide. To an unprecedented degree it takes account of the role of people as providers and consumers of health services, as financial contributors to health systems, as workers within them, and as citizens engaged in their responsible management or stewardship. Health systems provide the critical interface between life-saving, life-enhancing interventions and the people who need them. If health systems are weak, the power of these interventions is likewise weakened, or even lost. Health systems thus deserve the highest priority in any efforts to improve health or ensure that resources are wisely used. In recent decades, health systems have contributed enormously to better health for most of the global population. As the new century begins, they have the potential to achieve further improvements in human wellbeing, especially for the poor. But very little has yet been done to unravel the complex factors which explain good or bad performance by individual health systems. Given equal resources, why do some succeed where others fail? Is performance simply driven by the laws of supply and demand, or does another logic apply? Why is dissatisfaction with services so widespread, even in wealthy countries offering the latest interventions? If systems need improvement, what tools exist to measure performance and outcomes? These are some of the many questions addressed in this report. Drawing upon a range of experiences and analytical tools, the report traces the evolution of health systems, explores their diverse characteristics, and uncovers a unifying framework of shared goals and functions. Using this as a basis for analysis, the report breaks new ground in presenting an index of health system performance based on three fundamental goals: improving the level and distribution of health, enhancing the responsiveness of the system to the legitimate expectations of the population, and assuring fair financial contributions. As the report convincingly argues, good performance depends critically on the delivery of high-quality services. But it relies on more than that. Health systems must also protect citizens from the financial risks of illness and meet their expectations with dignified care. The report goes on to show how the achievement of these goals depends on the ability of each system to carry out four main functions: service provision, resource generation, financing, and stewardship. Chapters devoted to each function offer new conceptual insights and practical advice on how to assess performance and achieve improvements with available resources. In doing so The World Health Report 2000 aims to stimulate a vigorous debate about better ways of measuring health system performance and thus finding a successful new direction for health systems to follow. By shedding new light on what makes health systems behave in certain ways, WHO also hopes to help policy-makers understand the many complex issues involved, weigh their options, and make wise choices.