Vienna's Arnold Schoenberg Choir performs music from the Renaissance to the contemporary era, including, at times, that of its namesake, but it has pursued a special focus on Baroque music. The choir also participates in operatic productions and since 2006 has been the opera chorus in residence at the Theater an der Wien. The Arnold Schoenberg Choir (German: Arnold Schoenberg-Chor) was founded in 1972 by Erwin Ortner, who remains its artistic director. Although it is composed of students and graduates of the Vienna University for Music and the Performing Arts, its 60 singers are employed in a fully professional capacity. The choir took its name to honor composer Arnold Schoenberg but has never put his music in the foreground. It has a large repertory extending from the Renaissance to music of the present day but has focused on Baroque music, often collaborating with historical performance specialist Nikolaus Harnoncourt and his Concentus Musicus Wien instrumental ensemble. Harnoncourt led the group in two of its earliest recordings, one of Mozart's Requiem in D minor, K. 626, and one of Handel's oratorio Samson, HWV 57. Those recordings appeared on the Teldec label, of whose catalog the Arnold Schoenberg Choir remained a staple for many years. Notable recordings include a complete seven-volume set of Schubert's rarely heard secular choral music (1996), directed by Ortner; that album won the Schallplattenkritik prize, a Diapason d'Or, and the Japanese recording academy's grand prize. In 2016, the choir participated in Harnoncourt's final recording, of Beethoven's Missa Solemnis, on the Sony Classical label. The group has been heard in various operatic productions, including those of operas of Mozart, Schubert's rarely heard Fierabras, and Olivier Messiaen's Saint-François d'Assise. The Arnold Schoenberg Choir often appears at Austrian festivals such as the Salzburg Festival, the Vienna Festival Week, and Wien Moderne. Its live season for 2021 included participation in the early allegorical opera La rappresentatione di anima e di corpo of Emilio de' Cavalieri. The Arnold Schoenberg Choir returned to the recording scene that year on a recording of Erwin Schulhoff's opera Flammen.