This dissertation presents an analysis of José Siqueira’s Oito Canções Populares Brasileiras (Eight Popular Brazilian Songs), published in 1955 for voice and piano. The analyses show how the composer used musical materials from Northeastern folklore, Native Brazilian culture, and popular urban musical traditions in the composition of this song set. The author also suggests interpretative performance approaches that take into consideration the musical, textual, and sociocultural aspects of these songs. As an aid to the foreign singer who wishes to perform this repertoire, this research also presents English-language translations and International Phonetic Alphabet transcriptions of the song texts. In addition to analyses and interpretative suggestions, this dissertation discusses topics such as the history of Brazilian art song; Siqueira’s biography, his vocal works, and compositional style; aspects of lyric diction of Brazilian Portuguese and the necessary adaptations for an expressive interpretation of the Oito Canções Populares Brasileiras; Siqueira’s Trimodal System (the first time this compositional system is presented in the English language); and new and more accurate information on the actual publication dates of the Oito Canções Populares Brasileiras. The analyses of the songs show Siqueira’s refined and versatile métier as a composer. Natiô reflects Native Brazilian culture through the use of a chant by the Pareci tribe and the use of two mixed scales to portray the exotic character attributed to this culture at the time. In Loanda and Maracatu, the composer uses several rhythmic cells that are characteristic of the folkloric tradition known as Maracatu. Vadeia Cabocolinho, Benedito Pretinho, and A Dança do Sapo reflect the Coco de Embolada, a folkloric tradition from the Northeastern region involving a soloist who displays sharp-tongued improvisational skills and a group singing a refrain in a syncopated rhythm. In these songs, Siqueira uses music modes commonly found in Northeastern folkloric music. Nesta rua and Foi numa noite calmosa reflect the Brazilian modinha and seresta through extensive use of musical elements that characterize that musical genre and tradition, such as descending melodic motion, use of minor keys, and short melodic fragments separated by rests. The use of these compositional procedures in combination with a clear twentieth-century musical language confirms Siqueira’s two aesthetic orientations: Folkloric Nationalism (when the composer uses the pure elements of folklore) and Essential Nationalism (when the composer draws inspiration from folklore and creates his own musical language). The diversity reflected in this song set makes it a strong representation of the rich Brazilian art song tradition.