Arnold Schoenberg ( [ˈaːrnɔlt ˈʃøːnbɛrk]) (13 September 1874 - 13 July 1951) was an Austrian and later American composer, associated with the expressionist movement in German poetry and art, and leader of the Second Viennese School. He used the spelling Schönberg until his move to the United States in 1934.blank">http://sfsymphony.com/templates/pgmnote.asp?nodeid=3746&seasonid=9&eventid=1167 Schoenberg was known for extending the traditionally opposed German Romantic traditions of both _Brahms and Wagner, and also for his pioneering innovations in atonality—during the rise of the Nazi party in Austria, his music was labeled, alongside swing and jazz, as degenerate art. He famously developed twelve-tone technique, a widely influential compositional method of manipulating an ordered series of all 12 possible notes. He also coined the term developing variation, and was the first modern composer to embrace ways of developing motives without resorting to the dominance of a centralized melodic idea.

Schoenberg was also a painter, an important music theorist, and an influential teacher of composition; his students included Alban Berg, Anton Webern, and later John Cage. Many of Schoenberg's practices, including the formalization of compositional method, and his habit of openly inviting audiences to think analytically, are echoed in avant-garde musical thought throughout the 20th century. His often polemical views of music history and aesthetics were crucial to many of the 20th century's significant musicologists and critics, including Theodor Adorno, Charles Rosen, and Carl Dahlhaus.

Schoenberg's archival legacy is collected at the Arnold Schönberg Center in Vienna.