A concerto for orchestra is a musical work in which various instruments or groups of instruments play passages in dialogue with the whole orchestra. The particular instruments that perform in this way may vary from one work to another, and different instruments may take over in different parts of the work. The concerto for orchestra is different from the usual concept of a concerto, which features one particular instrument — such as an oboe or clarinet — that engages in a dialogue with the orchestra throughout the work. This musical form has not been used very frequently by composers, but there were some notable examples of this form written in the 20th century.
Works in the form of a concerto for orchestra were written by a variety of composers in the 20th century, including Paul Hindemith and Leonard Bernstein. The most well known example of this form was written by Bela Bartok in 1943. The concerto is in the composer's frequently used arch form, in which there is symmetry among opposite movements; for example, the first and last movements have some similar characteristics. The concerto form is evident throughout the work and, in the second movement, instruments such as the bassoons are given passages for themselves. In other parts of the work, groups of instruments such as woodwinds or strings take up the dialogue with the orchestra.
The form in which the concerto for orchestra is written varies greatly from one work to the next. Bartok wrote his work in an arch form, in five movements, while Bernstein wrote his work in two movements. The work by Thea Musgrave is written in five connected movements and builds up to a confrontation between the solo instruments and the orchestra. In the first decade of the 21st century, Christopher Rouse wrote a concerto for orchestra in two general sections, each containing its own movements and allowing each soloist a chance to play a lyrical or virtuoso passage.
The concerto for orchestra differs from the sinfonia concertante of the Baroque Period. Although that musical form also used a number of instruments to play in contrast with the whole ensemble, the concerto for orchestra does not use the same groups of concerto instruments in the course of the whole work. Certain symphonies of the Classical and later periods also feature solo instruments in some passages; however, the concerto for orchestra features such passages throughout the whole work and as an integral feature of the work.