Composer, Conductor. He is remembered as one of the leading orchestra conductors of the 20th century. Born to a Jewish family in Breslau, Silesia Province, then in Germany (now Wrocław, Poland), he studied music first at the Hoch Conservatory in Frankfurt, Germany and later at the Stern Conservatory in Berlin, Germany. In 1905 he met composer/conductor Gustav Mahler while conducting the off-stage brass at a performance of Mahler's "Symphony No. 2, Resurrection." They became friends, and he became conductor at the German Opera in Prague, Czechoslovakia (now Czech Republic) in 1907 on Mahler's recommendation. In 1910 he assisted Mahler in the premiere of his "Symphony No. 8, Symphony of a Thousand." From 1910 until 1927 he held conducting positions in Germany, including Hamburg, Barmen, the Strasbourg Opera, the Cologne Opera, and the Wiesbaden Opera House. In 1927 he became the conductor at the Kroll Opera in Berlin, where he enhanced his reputation as a champion of new music, including Leos Janacek's "From the House of the Dead," Arnold Schoenberg's "Erwartung," Igor Stravinsky's "Oedipus Rex," and Paul Hindemith's "Cardillac." In 1933, when the Nazi Party took power in Germany, he immigrated to the US with his family and settled in Los Angeles, California where he was appointed Music Director of the Los Angeles Philharmonic, and became a US citizen in 1937. He had a difficult time adjusting to Southern California, a situation exacerbated by repeated manic-depressive episodes, reportedly as a result of severe cyclothymic bipolar disorder. To his dismay, he was passed over for the lead conductor position of the New York and Philadelphia Philharmonic Orchestras. In 1939 he was diagnosed with a brain tumor the size of a small orange and the subsequent surgery to remove it left him partially paralyzed. He became depressed and was institutionalized. He managed to escape, but was soon found and returned to the institution. Though he would occasionally conduct the Los Angeles Philharmonic after that, he lost his post of Music Director. Furthermore, his erratic behavior during manic episodes made him an undesirable guest to US orchestras, and the late flowering of his career centered in other countries. After the end of World War II, he returned to Europe to work at the Budapest Opera (1947 to 1950). Finding Communist rule in Hungary increasingly irksome, he became an itinerant conductor, guest conducting the Royal Danish Orchestra, Montreal Symphony Orchestra, Cologne Radio Symphony Orchestra, Concertgebouw Orchestra, and the Philharmonia of London. A severe fall during a visit to Montreal, Canada in 1951 forced him subsequently to conduct seated in a chair. Later, a severe burning accident, which resulted from his smoking in bed, further paralyzed him. In the early 1950s he experienced difficulties arising from his US citizenship. American union policies made it difficult for him to record in Europe, and his left-wing views made him increasingly unpopular with the US State Department as well as the Federal Bureau of Investigation, and in 1952 the US refused to renew his passport. In 1954 he returned to Europe again and acquired a German passport. That year, his career was turned around by the London-based producer Walter Legge, who recorded him conducting works in Beethoven, Brahms and much else with his hand-picked orchestra, the Philharmonia, for the EMI label. In 1959 he became the first principal conductor of the Philharmonia and afterwards he made his home in Switzerland. In 1971 he retired from conducting and died in Zurich, Switzerland at the age of 88. He is the father of actor Werner Klemperer, known for his portrayal of German prisoner of war camp commander 'Colonel Klink' on the CBS television sitcom "Hogan's Heroes," that aired from 1965 until 1971. He was an Honorary Member of the Royal Academy of Music. Many of his recordings are still available on CDs.