The distinctive music of Alberto Ginastera, one of the major Argentine composers of the mid-20th century, has enjoyed broad international popularity. His early works were influenced by Argentine folk music and had a strong populist flavor, but in the late '50s he began to adopt serial and experimental techniques. Ginastera's mature music is characterized by a sophisticated synthesis of the avant-garde with Argentine folk traditions and is often strongly lyrical and rhythmically energetic. His major works include the ballet Estancia, the First Piano Sonata, Variaciones concertantes for chamber orchestra, the First Piano Concerto, and the controversial opera Bomarzo.