The turn towards a ‘Social Investment’ approach to welfare implies deploying resources to enhance human capital and mobilise the productive potential of citizens, starting in early childhood. Many influential academic and policy advocates present it as a new paradigm for the 21st Century. The book is structured in three parts around the social investment themes of: interventions in early life, labour market activation, and social solidarity. Empirical chapters offer original evidence from ten European countries: Italy, UK, Sweden, Finland,Greece, Germany, Poland, the Netherlands, Hungary, and Spain. Each of these chapters uncovers regional and local realities of social investment policies and services. Editorial chapters overview the conceptual landscape and synthesise key advances in thinking about the social investment 'paradigm', informed by original insight into what implementation of its principles can look like at street level.