The quatuor concertant is a special form of string quartet that developed in Paris around 1775 and became one of the leading genres of Parisian music until the French Revolution.
The name "quatuor concertant" appears often in the scores of string quartets published in Paris, not always corresponding to the characteristics below.
While the term initially was simply used to highlight the soloistic character of the piece, from around 1776 on it is mainly used for string quartets in which the different voices alternately take the leading role.
Characteristic of the quatuor concertants are the alternating solos in the different voices, sometimes including the cello, catchy, often operatic, melodies, and a great ingenuity in harmonic, rhythmic, and melodic detail.
A special form is the Quatuor d'airs connus, which is based on the variation of a popular melody, derived either from folksong or from an opera aria.