This chapter is the introduction to the volume on social protection in Brazil, India, China, and South Africa. The Introduction outlines an ideational and historical approach to social protection in the Global South to contribute to a theory of “social policy in development contexts”, which is a desideratum. The Introduction also provides basic data on the four countries (Brazil, India, China, and South Africa) and summaries of all the chapters in the book. Three research gaps are identified: scarcity of historical research; scant attention to ideas and instead a dominant focus on interests; and insufficient use of historical sources. This volume contributes to filling these gaps through a historical, idea-centred, and source-based approach. A multi-layered model of social ideas—the “onion skin model”—is developed that has the “social question” as its pivot.