(1874-1951), Austrian born composer, creator of the twelve-tone system of musical composition, and one of the most influential composers of the 20th century.

Schoenberg was born on Sept. 13, 1874, to a Jewish family in Vienna. He taught himself composition, with help in counterpoint from the Austrian composer Alexander Zemlinsky (1871-1942), and in 1899 produced his first major work, the tone poem Verklärte Nacht (Transfigured Night) for string sextet. In 1901 he married Zemlinsky's sister Mathilde (1877-1923), with whom he had two children. The couple moved to Berlin, where for two years Schoenberg earned a living by orchestrating operettas and directing a cabaret orchestra.

Career in Vienna, Berlin, and the U.S.
In 1903 Schoenberg returned to Vienna to teach. There he met his most successful students, the Austrian composers Anton Webern and Alban Berg, who became his close friends. In his compositions, Schoenberg employed far-reaching harmonies, a trait that later developed into atonality. Because of this, riots erupted at both premieres of his first two string quartets in 1905 and 1908. Such experiences led him often to feel persecuted by a public that could not understand his music.
Schoenberg also began painting during these years and exhibited his work with a group of artists in the circle of the Russian painter Wassily Kandinsky. This period was marked by tragedy when Mathilde had an affair with his painting teacher, who committed suicide after she returned to Schoenberg. In 1911, the year in which Schoenberg published his book Theory of Harmony, he accepted a teaching position in Berlin. There he composed one of his most influential works, Pierrot Lunaire (1912). He returned to Vienna in 1915. The interruptions occasioned by World War I, combined with Schoenberg's search for a way to ensure logic and unity in atonal music, prevented him from producing many works between 1914 and 1923. By 1923, however, he had completed the formulation of his twelve-tone method of composition. Mathilde's death that same year was a serious blow to Schoenberg, but in 1924 he met and married Gertrud Kolisch (1898-1967), the sister of an Austrian violinist. With the invitation in 1925 to teach composition at the Academy of Arts in Berlin, Schoenberg finally obtained a prestigious position, financial security, and a stable family life. In 1932, the year the couple's daughter was born, he completed the second act of his opera Moses und Aron (produced posthumously, 1957).
Schoenberg and his family fled Nazi Germany to Paris in 1933. In 1934 they immigrated to the U.S., and he accepted a teaching position in Boston. The next year, because of his health, they moved to Los Angeles, where his two youngest sons were born. After a year as a lecturer at the University of Southern California (1935), he taught at the University of California at Los Angeles from 1936 to 1944. He became a U.S. citizen in 1941. Schoenberg fell seriously ill in 1946, and at one point his heart stopped beating; this experience is reflected in his String Trio (1946), written after his recovery. In retirement he continued to teach and to compose. He died on July 13, 1951, in Los Angeles.

Musical Evolution.
Schoenberg's musical style progressed from late 19th-century romanticism to the twelve-tone technique. His early tonal works are reminiscent of the music of the German composer Johannes Brahms, but before long he assimilated the chromaticism of the German composer Richard Wagner. In works such as Verklärte Nacht Schoenberg achieved intensity of feeling through rich harmonies and long soaring melodies supported by a dense contrapuntal texture of short, constantly varying motives. Beginning about 1907 these traits became even more pronounced in his expressionist works, in which tonality was abandoned and musical form became compressed. The prime example from this period is Pierrot Lunaire; in this setting of macabre verse, the accompanying chamber ensemble employs a different combination of instruments for each of the 21 poem-based songs of the cycle, and the vocal soloist uses the Sprechstimme, (Ger., "speech voice"), or Sprechgesang ("speech song") a blend of speech and song.
About 1920 Schoenberg began to formulate his twelve-tone technique and to draw on classical musical forms to structure his compositions. All his styles, however, are distilled in his most massive attainment, Moses und Aron. Schoenberg occasionally returned to tonal composition, but in the majority of his works of the 1930s and '40s he attempted to synthesize the twelve-tone technique with the formal principles he had employed during his expressionist period. This synthesis can be heard in his one-movement Piano Concerto (1942) and in the monumental String Trio.
Through Schoenberg and his students, the twelve-tone method became a dominating force in mid-20th-century composition and exerted a profound influence on the course of Western music.