New social risks, ranging from profound transformations in labour markets to rising inequality and the climate crisis, are reshaping contemporary societies and demanding innovative forms of social policy. This book argues that the critical expansion of public social services is central to addressing these challenges. Securing and investing in public services, particularly the social provision of education and health care, not only fosters well-being but also contributes to building equitable, low-carbon economies and generating quality employment. The book draws on a wide range of theoretical traditions, including the capability approach, development studies, welfare state scholarship, and the UK’s Universal Basic Services perspective. It also advances a novel conceptual framework: the “constitutive welfare state.” This framework reconceptualizes public social services as an economic sector in their own right, with far-reaching structural consequences. Blurring the often overdrawn boundary between Global North and Global South experiences, the ensuing empirical analysis turns to Brazil as a Global South case that serves both as a concrete illustration and as a broader laboratory for the policies advanced in this book. The Brazilian case provides estimates of the macroeconomic, social, and ecological effects of expanding these services, including their potential to generate low-carbon, equitable employment and to narrow gender and racial wage differentials. It also addresses the main constraints such an agenda would confront. The book will be of interest to scholars and students of development, welfare state studies, social investment, well-being, labour markets, economic inequality—including gender and racial inequality—and distributional macroeconomics.