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The earliest string trio form consisted of two violins and a cello, a grouping which had grown out of the Baroque trio sonata, while later string trios more commonly are scored for violin, viola, and cello (Tilmouth and Smallman 2001).
Beginning in the second half of the 18th century, although the trio configuration for two violins and cello was not wholly abandoned in classical chamber music (even during the 19th century), the scoring for violin, viola, and cello began to take precedence. Joseph Haydn appears to have been the first composer to use this combination (Tilmouth and Smallman 2001), though he was soon emulated by Luigi Boccherini (Kennedy 1994).
Writing for a violin, viola and cello trio provides a wide palette of textures and colors for a skilled composer. The leaner instrumentation (as compared to the more common string quartet) also poses compositional challenges especially within a musical tradition typified by four-part harmony writing. In the 19th and 20th centuries countless composers after Mozart and Beethoven have taken up this challenge, including Lennox Berkeley, Carlos Chávez, Henry Cowell, Jean Cras, Paul Dessau, Ernst von Dohnányi, Hanns Eisler, Jean Françaix, Heinrich von Herzogenberg, Paul Hindemith, Gideon Klein, Frank Martin, Bohuslav Martinů, Darius Milhaud, Ernest John Moeran, Manuel Ponce, Max Reger, Terry Riley, Alexis Roland-Manuel, Miklós Rózsa, Arnold Schoenberg, Franz Schubert, William Schuman, Jean Sibelius, Robert Simpson, Richard Strauss, Sergei Taneyev, Heitor Villa-Lobos, Anton Webern, and Eugène Ysaÿe.
More recently, notable string trios have been written by Murray Adaskin, Alain Bancquart, Robert Carl, Pascal Dusapin, Donald Erb, Karlheinz Essl, Brian Ferneyhough, Berthold Goldschmidt, Sofia Gubaidulina, Bertold Hummel, Talivaldis Kenins, Ernst Krenek, Helmut Lachenmann, Paul Lansky, Ljubica Marić, Krzysztof Meyer, Krzysztof Penderecki, Wayne Peterson, Wolfgang Rihm, Bogusław Schaeffer, Alfred Schnittke, Karlheinz Stockhausen, Graham Waterhouse, Charles Wuorinen, La Monte Young, Iannis Xenakis, and Ellen Taaffe Zwilich.
While string trio ensembles are certainly more rare than string quartets, there have been, and continue to be, ensembles dedicated to performing and recording the string trio repertoire.
Examples of more unusual string trio configurations include Wolfgang Amadeus Mozart's trio for two violins and double bass, and Antonín Dvořák's and Frank Bridge's trios for two violins and viola. Others who have written trios for this combination include Robert Fuchs (three, two in his opus 61 and one in his opus 107) and Sergei Taneyev (his op. 21). Wilhelm Killmayer has written a trio (1975) for the similar combination of two violins and cello and Stefan Hakenberg scored the third movement of The Displacement Map (2002), entitled "Monochrome", for this combination. The Masada String Trio, a group that performs the music of John Zorn, is configured for violin, cello, and double bass.
- Ludwig van Beethoven: String Trios 1–5 (1794–1998)
- Luigi Boccherini: String Trios G 77 – G 142
- Carlos Chávez: Invención II (1965)
- Karlheinz Essl: à trois/seul for string trio (1998)
- Brian Ferneyhough: String Trio (1995)
- Joseph Haydn: 21 String Trios
- Ernesto Halffter: Homenajes
- Heinrich von Herzogenberg: String Trios Op.27 Nos. 1 & 2
- Yefim Golyshev: String Trio, subtitled Zwölftondauer-Komplexe (twelve-tone-duration complex) (1925)
- Wilhelm Killmayer:
- Trio for two violins and cello (1975)
- Trio (1984)
- Ernst Krenek
- String Trio, op. 118
- String Trio Parvula Corona Musicalis: ad honorem Johannis Sebastiani Bach, op. 122
- String Trio in 12 Stations, op. 237
- Donald Martino: String Trio (1954)
- Bohuslav Martinů
- String Trio No. 1, H. 136 (1923)
- String Trio No. 2, H. 238 (1934)
- Wolfgang Amadeus Mozart: Divertimento KV 563 (1788)
- Wayne Peterson: String Trio (2007)
- Max Reger
- String Trio No. 1 Op. 77b in A minor
- String Trio No. 2 Op. 141b in D minor
- Carl Reinecke: String Trio in C minor, Op. 249
- Guy Ropartz: Trio in A minor for Strings (1934–35)
- Alfred Schnittke: String Trio (1985)
- Arnold Schoenberg: String Trio, Op. 45 (1946)
- Jean Sibelius:
- Andantino in A major (1889)
- Suite (Trio) in A major (1889, revised 1912)
- Trio in G minor (1893–94)
- Nikos Skalkottas: String Trio No. 2 (1935)
- Karlheinz Stockhausen: Hoffnung (2007)
- Sergei Taneyev: String Trio in D major (1879/1880)
- Graham Waterhouse: Epitaphium (2007)
- Anton Webern: String Trio (1927), his first instrumental work using the twelve tone technique
- Egon Wellesz
- String Trio, op. 86 (1962)
- Four Works for string trio, op. 105 (1969, second version 1971)
- Charles Wuorinen: String Trio (1968)
- Iannis Xenakis: Ikhoor (1978)
- La Monte Young: Trio (1958)
- Kennedy, Michael (ed.). 1994. "String Trio". The Oxford Dictionary of Music, second edition revised, associate editor Joyce Bourne. London and New York: Oxford University Press. ISBN 0198691629.
- Tilmouth, Michael, and Basil Smallman. 2001. "String Trio". The New Grove Dictionary of Music and Musicians, second edition, edited by Stanley Sadie and John Tyrrell. London: Macmillan Publishers.
- Downs, Philip G. 1992. Classical Music: The Era of Haydn, Mozart, and Beethoven. The Norton Introduction to Music History. New York: W.W. Norton. ISBN 039395191X.
- Holloway, Robert James. 1962. "String Trio Literature of the Twentieth Century". MM Thesis. Washington, DC: American University.
- Unverricht, Hubert. 1969. Geschichte des Streichtrios. Mainzer Studien zur Musikwissenschaft 2. Tutzing: Hans Schneider.