Closing the Coverage Gap discusses how social pensions and other retirement income transfers can be used to close the coverage gap of mandatory pension systems. The book is organized in three parts. The first part makes the case for these programs by assessing the extent of the coverage gap around the world and evaluating the vulnerability to poverty of the elderly. The second part reviews the experiences of low, middle and high income countries with the design and implementation of retirement income transfers. The last part focuses on design issues. It analyses the incentive effect of these programs on labor supply and savings, fiscal costs, the role of targeting mechanisms, and alternatives in terms of institutional design and administration. The book also discusses the role of promising instruments such as matching contributions to reach parts of the informal sector.