Tropicalismo, or Tropicália, evolved in opposition to stifling social complacency in politically tense late 60s Brazil. Tropicalia artists were bound together more by an ideology of social awareness and creativity than any stock musical descriptors. However, a loose description would cite elements of bossa nova, psychedelia, folk, Portuguese, and African music but reinterpreted through unorthodox song structures. The common bond between the major musicians in the genre – Caetano Veloso, Gilberto Gil, and Os Mutantes – tended to be topical, elegantly poetic lyrics. Tropicália ended in 1969 when Veloso and Gil were exiled by their government. Although neither the original movement nor any later outgrowth have attained commercial success outside Latin America, tropicalia has been embraced by Beck, Devendra Banhart, and David Byrne, whose Luaka Bop label reissued many of the genre’s key artists. Today, Gilberto Gil has been named the Minister of Culture under the new Brazilian government.

Documentary on Os Mutantes
Extensive Tropicalia site
Tropicalia on AllMusic.com
PBS Culture Shock: Tropicalia
The Brazilian Sound - Tropicalia
PBS: Caetano Veloso