Formed by Argentinean musicians in São Paulo (São Paulo) in the mid-'60s as a vocal/instrumental rock group, the Beat Boys were an important reference in a moment when Tropicália was being geared, as they provided the rock spirit that Caetano Veloso was looking for at his iconoclastic appearance at the III Festival de Música Popular Brasileira/FMPB (Festival of Brazilian Popular Music Festival, Paramount Theater, TV Record, São Paulo, 1967), when their performance of "Alegria, Alegria" (Caetano Veloso) provoked virulent reactions by the audience that were amplified throughout public opinion and yielded a marked polarization between nationalists and transnationalists against the electric guitar. That edition of the festival represented the first time in which rock music was presented in a similar situation mixed with Brazilian popular music. Along with the Beat Boys, the Os Mutantes was the other rock group present at the event, accompanying Gilberto Gil on "Domingo no Parque." The Beat Boys also participated in the recording of "Alegria, Alegria" with Caetano Veloso. In 1968, they released an individual recording, Beat Boys.