This chapter aims to provide an account of the evolution of social policies in Brazil’s legislation from the 1930s to this date and to identify the main causes (in particular the motivational ideas) that led to the legal entrenchment of such policies. The main focus will be on social policies entrenched in the highest level of legislation in Brazil, ie its constitutions. The chapter is organised as follows. Section 2 presents a historical account of the evolution of social policies in Brazil’s constitution and legislation from the 1930s to the 1988 Constitution (still in force), as well as some important infra-constitutional developments such as the Family Grant programme. Section 3 discusses some of the most often mentioned causes (including the ideas) behind the development of social policy legislation in Brazil during that period. The concluding section comments briefly on the reality of social policies on the ground and how they differ, by some margin, from the legal text, yet have made a non-trivial difference to the well-being of the Brazilian people.