Arnold Schoenberg or Schönberg (/ˈʃɜːrnbɜːrɡ/, US also /ˈʃoʊn-/; German: [ˈʃøːnbɛɐ̯k] (￼listen); 13 September 1874 – 13 July 1951) was an Austrian-born composer, music theorist, teacher, writer, and painter. He is widely considered one of the most influential composers of the 20th century. He was associated with the expressionist movement in German poetry and art, and leader of the Second Viennese School. With the rise of the Nazi Party, Schoenberg's works were labeled degenerate music, because they were modernist and atonal. He emigrated to the United States in 1933, becoming an American citizen in 1941.