Introduction and Allegro for Harp, Flute, Clarinet and String Quartet (Introduction et allegro pour harpe, flûte, clarinette et quatuor) is a chamber work by Maurice Ravel. It is a short piece, typically lasting between ten and eleven minutes in performance. It was commissioned in 1905 by the Érard harp manufacturers to showcase their instruments, and has been described as a miniature harp concerto. The premiere was in Paris on 22 February 1907.

The work has been arranged for piano and for large orchestral forces but the version for seven instruments is usually performed, and has been recorded many times. Harpists who have featured in recordings include Lily Laskine, Nicanor Zabaleta, Osian Ellis, Markus Klinko, Lavinia Meijer and Marie-Pierre Langlamet.

To showcase its new chromatic harp, the Pleyel company commissioned Claude Debussy in 1904 to write his Danses sacrée et profane for harp and orchestra. The rival Érard company responded by commissioning Maurice Ravel to write a piece to display the expressive range of its double-action pedal harp.

Ravel completed his Introduction and Allegro for a septet of harp, flute, clarinet and string quartet in June 1905, dedicating it to Albert Blondel, director of Maison Érard. For Ravel, composition was generally slow and painstaking, but he wrote the Introduction and Allegro at what for him was breakneck speed, to complete it before embarking on a boating holiday with friends. He wrote at the time:

The premiere was given on 22 February 1907 at an all-Ravel concert presented by the Cercle Musical at the Hôtel de la Société française de photographie in Paris. The players were Micheline Kahn (harp), Philippe Gaubert (flute), Ernest Pichard (clarinet), and the Quartet Firmin Touche; the performance was conducted by Charles Domergue.

The British premiere was on 4 September 1907 at a Henry Wood Promenade concert, with Alfred Kastner as harp soloist. Ravel later conducted the work in Britain, first at the Bechstein Hall, London, in December 1913, with Gwendolen Mason as harpist, and in concerts of his works at both the Aeolian Hall, London and the town hall, Oxford in October 1928.

The American premiere was at Aeolian Hall in New York on 3 December 1916 in a concert featuring the harpist Carlos Salzedo, who gave the American premiere of Debussy's Danses sacrée et profane in the same programme. At the first performance in Australia, at the Conservatorium Hall, Sydney, in November 1917, the piece was so enthusiastically received that it had to be immediately repeated.

The full title of the work in the published score gives primacy to the harp: "Introduction et Allegro pour Harpe avec accompagnement de Quatuor à Cordes, Flûte et Clarinette". Although some commentators have emphasised the chamber nature of the piece, and challenged the view of it as a concertante work, the Ravel scholar Arbie Orenstein writes, "Ravel apparently wished to stress the privileged position of the harp, and the composition should thus be considered a miniature harp concerto rather than a septet".