The modern mathematics movement, which originated in Europe and in the United States, reverberated in Brazil, more so than in other Latin American countries. In order to understand the local extension of this movement, elements of the reality of secondary education in Brazil are considered as well as the local interpretations and appropriations of the new curricular proposals, in particular by the Grupo de Estudos em Ensino de Matemática (Study Group on Mathematics Teaching – GEEM), created in the city of São Paulo in 1961. The reach of a movement that promised the “modernisation” of teaching, and that identified modernisation with democratisation, must also be understood within the context of optimism and a belief in the benefits of technical progress.