The concerto grosso (pronounced [konˈtʃɛrto ˈɡrɔsso]; Italian for big concert(o), plural concerti grossi [konˈtʃɛrti ˈɡrɔssi]) is a form of baroque music in which the musical material is passed between a small group of soloists (the concertino) and full orchestra (the ripieno or concerto grosso). This is in contrast to the solo concerto which features a single solo instrument with the melody line, accompanied by the orchestra. 
The form developed in the late seventeenth century, although the name was not used at first. Alessandro Stradella seems to have written the first music in which two groups of different sizes are combined in the characteristic way. The name was first used by Giovanni Lorenzo Gregori in a set of 10 compositions published in Lucca in 1698.
The first major composer to use the term concerto grosso was Arcangelo Corelli. After Corelli's death, a collection of twelve of his concerti grossi was published; not long after, composers such as Francesco Geminiani, Pietro Locatelli and Giuseppe Torelli wrote concertos in the style of Corelli. He also had a strong influence on Antonio Vivaldi.
Two distinct forms of the concerto grosso exist: the concerto da chiesa (church concert) and the concerto da camera (chamber concert). (See also Sonata for a discussion about sonatas da camera and da chiesa.) The concerto da chiesa alternated slow and fast movements; the concerto da camera had the character of a suite, being introduced by a prelude and incorporating popular dance forms. These distinctions blurred over time.
Corelli's concertino group consisted of two violins and a cello, with a string section as ripieno group. Both were accompanied by a basso continuo with some combination of harpsichord, organ, lute or theorbo. Handel wrote several collections of concerti grossi, and several of the Brandenburg Concertos by Bach also loosely follow the concerto grosso form.
The concerto grosso form was superseded by the solo concerto and the sinfonia concertante in the late eighteenth century, and new examples of the form did not appear for more than a century. In the twentieth century, the concerto grosso has been used by composers such as Igor Stravinsky, Ernest Bloch, Ralph Vaughan Williams, Bohuslav Martinů, Malcolm Williamson, Henry Cowell, Alfred Schnittke, William Bolcom, Heitor Villa-Lobos, Andrei Eshpai, Eino Tamberg, Krzysztof Penderecki, Jean Françaix and Philip Glass. While Edward Elgar may not be considered a modern composer, his romantic Introduction and Allegro strongly resembled the instrumentation setup of a concerto grosso.
Though the concertino is the smaller of the two groups, its material is generally more virtuosic than that of the ripieno. Further, the concertino does not share thematic material with the ripieno, but presents unique ideas. This contrast of small group to large group and one thematic group against another is very characteristic of Baroque ideology — similar to terraced dynamics where the idea is significant contrast.
- "The Baroque Concerto Grosso". Retrieved October 6, 2016.
- Treccani Dizionario Biografico
- "Concerto Grosso". Britannica. Retrieved October 6, 2016.
- "Concerto grosso". Retrieved October 6, 2016.
- "Elgar – Introduction and Allegro for Strings". Retrieved October 6, 2016.
- Greenberg, Robert (2006). How to Listen to and Understand Great Music (3rd ed.). The Great Courses. p. 75. ISBN 9781598032703.
- Hutchings, Arthur. "Concertino". Grove Music Online. Oxford Music Online. Oxford University Press. Retrieved 14 April 2016. (subscription required (. ))
- Bennett, R. (1995). Investigating Musical Styles. Cambridge: Cambridge University Press.