In high-income countries, the percent of the population covered under mandatory old-age pension programs is typically high but often incomplete; in low- and middle-income countries, coverage is low and even stagnant. At the same time, older people are less able to rely on family and community support as a result of growing urbanization and migration. And low-income workers and the poor simply cannot save enough to prepare for their old age. As a response, many countries are considering or have already implemented various forms of retirement income transfers aiming to guarantee a minimum level of income during old age. Despite the growing popularity of these programs, research assessing their success has been limited. 'Closing the Coverage Gap: The Role of Social Pensions and Other Retirement Income Transfers' brings together a group of renowned academics, policy analysts, and policy makers working in the area of pensions and public policy. They discuss how social pensions and other retirement income transfers can be used to close the coverage gap of mandatory pension systems: how they operate, when they can be appropriate, and how to make them work. The book reviews the experiences of low-, middle-, and high-income countries with the design and implementation of retirement income transfers. The book analyzes design issues related to financing, incentives, targeting mechanisms, and administration, and also identifies the role of promising instruments such as matching contributions to reach parts of the informal sector.