What are the objectives of social security and social assistance provisions? How can we establish whether these provisions are effective? How do countries differ in the design and effectiveness of their social security systems? This introductory textbook provides a foundation for the systematic study of social security and means-tested social assistance. The book is structured around a model of policy evaluation, which focuses attention on the multiple objectives and outcomes of social security and provides the basis for a multi-disciplinary approach. It progresses from an examination of the varied objectives of social security, via a consideration of key implementation issues, to the establishment of measures of effectiveness and efficiency.Throughout the text, theoretical issues are illustrated with reference to the experiences of six countries: the United Kingdom, the USA, Australia, Germany, Sweden and South Korea, to provide an international comparative framework. This is a key textbook for students of social and public policy and economics and essential reading for anyone interested in social security, social welfare and the welfare state.