In the 1920s, a revolutionary group of composers from the Rio neighborhood of Estácio de Sá that included Ismael Silva (1905-1978), Bide (Alcebíades Barcelos, 1902-1975), Armando Marçal (1902-1947), Nilton Bastos, and others charted a new course for the fledgling genre. In contrast to the maxixe-based sambas of Donga and Sinhô, the Estácio sambas featured a type of guide rhythm, or time-line, of Bantu African origin known in Rio as teleco-teco. This pattern — often played on the four-string cavaquinho or small frame drum called a tamborim — has come to shape the rhythmic structure of the genre ever since.

The Estácio composers also transformed their local bloco carnavalesco (informal street Carnaval group) into the first escola de samba or “samba school,” called Deixa Falar (Let Them Talk), founded on August 12, 1928. The name “Let Them Talk” was a reference to the rivalry that existed among Carnaval groups from different neighborhoods. Located near a school that graduated teachers who worked in the City school district, Deixa Falar was called a “samba school” because its leaders — considered professors of this new type of samba — were said to graduate sambistas. The term “samba school” conferred more respectability on the blocos from the favelas and working-class districts — which until that point were not allowed to parade downtown during Carnaval.

Deixa Falar sparked a revolution, and many other samba schools emerged, including Estação Primeira de Mangueira and Portela (founded in 1929 and 1935, respectively) — two of the oldest-surviving and most venerable samba schools of Rio today. The first unofficial samba school parade competition was held in 1932 in Praça Onze. In 1935, the federal Getúlio Vargas government officially recognized the samba schools and sanctioned them to parade in downtown Rio.