The overwhelming evidence of inequalities in health outcomes and in the use of health services calculated and disseminated by the World Bank and other development agencies in the last 10 years has energized global efforts to address the needs of the poor and socially vulnerable. These efforts have led to a renewed interest at the global and national levels in both understanding the causes of health sector inequalities and developing policies to tackle them. It is time to synthesize the new knowledge being generated from research and experimentation on addressing inequality. The main purpose of this book is to make available the accumulated knowledge of successful policy and analytical tools in this fight to reverse the vicious circle of income-poverty and ill health. The book presents both a practical set of analytical tools for understanding the causes of inequality in the use of health services and a menu of proven pro-poor policy actions. It is based on the evaluation of 14 successful policy changes in low- and middle-income countries in Africa, Asia, and Latin America, and a review of the published literature on inequality in the health sector.