Sonata form or sonata-allegro form is a musical form, a way of organising a work of music. The original idea of a central organizing form has been very widely used by classical composers since the 18th century, and was originally described by an Italian theorist as "a two part form" each part was repeated. By the early 19th century, Carl Czerny, a student of Beethoven's described it in terms of themes, which is how it is generally still described today. It was also considered to be the standard form for the first movement of any important work of instrumental music, for example a symphony, concerto, sonata or other works based on them, such as string quartets. For this reason, it is sometimes called first movement form, although this is somewhat of a misnomer, as it has been used in other movements of pieces. It is also sometimes known as compound binary form.

The central idea of the sonata-allegro form is to organize either harmony or themes from their being introduced, to their "development" or working out, through to a "recapitulation" where the original theme returns, and then, sometimes, to a "coda" which extends the music onward after the formal closure of the work. If this sounds complex, it is because it is an idea which has been progressively expanded on by new generations of composers, each seeking to refine, or enlarge, the same general shape to fit their own ideas. There are commonly played "sonata-allegro" movements which last only a few minutes, and some which extend for half an hour.

Table of contents
1 Outline of sonata form
2 The function of classical sonata form
3 Variation in classical sonata form
4 Sonata form in the Romantic era
5 Sonata form in the Modern era
6 Sonata form and other musical forms
7 Resources

Outline of sonata form

The classical sonata form movement in its simplest version consists of the following sections:

  • Exposition - the main themes of the piece are played for the first time. This section can be further divided into:
    • First group - this consists of one or more themes, all of them in the home key. So if the piece is in C major, all of the music in the first group will be in C major.
    • Transition - in this section the composer modulates from the key of the first subject to the key of the second.
    • Second group - one or more themes in a different key to the first group. If the first group is in a major key, the second group will usually be in the dominant, that is to say in a key a perfect fifth higher, so that if the original key is C major, the key of the music of the second group will be G major. If the first group is in a minor key, the second group will generally be in the relative major, so that if the original key is C minor, the second group will be in E flat major. The material in this section will usually be completely different to that of the first group, and sometimes will be in marked contrast to it. For example, the first group material may be strident and strongly rhythmic, with the second group more lyrical.
    • Codetta - a kind of finishing off section, which will bring the exposition section to a close with a perfect cadence in the same key as the second group. Often the codetta contains a sequence of themes, each of which arrives at a perfect cadence. The whole of the exposition may then be repeated.

  • Development - this generally starts in the same key as the exposition ended, and may move through many different keys during its course. It will usually consist of one or more themes from the exposition altered and occasionally juxtaposed with new material or themes. The development usually has a high degree of tonal and rhythmic instability when compared to the other sections. The development section may be quite short, or it may be extremely lengthy. At the end, the music will return to the home key and lead up to the:

  • Recapitulation - this is an altered repeat of the exposition, and consists of:
    • First group - usually in exactly the same form as it appeared in the exposition.
    • Transition - now altered so that it does not change key, but remains in the piece's home key.
    • Second group and codetta - usually in the same form as in the exposition, but now in the same key as the first group. If the first group was in a minor key, the second group and codetta may be shifted into the minor for the recapitulation, or they may be in the parallel major key (e.g., C minor/C major).

(It should be noted that the above terminology is not universally used: some writers speak of the first and second subjects rather than groups, others speak of the principal or main theme and the subordinate theme.)

First-movement concerto form

One notable variant on traditional sonata-allegro form is found in the first movement of the Classical concerto. In first-movement concerto form, the exposition is not repeated. Instead, it is played through in two different versions. The first features only the orchestra, not the solo instrument, and it remains in the tonic throughout the first and second thematic groups. Then, after a cadence on the tonic, the movement returns to its opening material, this time with the solo instrument. This second time, the form is as in standard sonata form, with a modulation to the dominant or relative major before the second group.

Additionally, towards the end of the recapitulation, there is an extended cadenza for the solo instrument without accompaniment. This has an improvisatory character (it may or may not actually be improvised) and serves, generally, to prolong the harmonic tension on a dominant chord before the orchestra ends the piece in the tonic.

The function of classical sonata form

Theorists have long sought to understand why the arrangements of keys and themes used in classical sonata form have held such importance for classical composers and their listeners. One influential view is that of Charles Rosen, who conceives the classical era's sonata form movement as a kind of dramatic journey through the system of musical keys. Modulations that move upward in the circle of fifths (in the direction of the sharp keys) increase musical tension, and modulations that move downward reduce it. Sonata form first increases tension through the move to the dominant (the crucial musical event of the exposition), then increases tension further in the development through the exploration of remote keys. The recapitulation resolves all this tension by returning everything to the tonic. He also argues that, over time, this idea would become the basis for all musical movements, regardless of their formal plan.

The use of the circle of fifths makes sense of a number of observations about the deployment of keys in the classical sonata form:

  • Use of keys other than the dominant for the second subject group generally go still higher than the dominant in the circle of fifths; see below.
  • Occasionally, the reappearance of the opening material at the beginning of the recapitulation is in the subdominant key (a famous example is Mozart's Piano Sonata K. 545), which serves the same resolving function as the tonic.
  • Secondary developments often also reach the subdominant key, with equivalent resolving function.

Variation in classical sonata form

The classical sonata form may be varied in a number of ways.


Quite often, a sonata form movement includes an additional section, the coda, which follows the end of the recapitulation. The coda rounds the movement off with a perfect cadence in the home key. Codas may be quite brief tailpieces, or they may be so lengthy as to be almost another development section.


Less often, the entire movement is preceded by a slow introduction. The introduction increases the weight of the movement, and also permits the composer to begin the exposition with a theme that would be too light to start on its own, as in Haydn's Drumroll Symphony. Usually, but not always, the introduction is excluded from the exposition repeat.

Occasionally the material of introduction reappears (in its original tempo) later in the movement. Often, this occurs in the coda, as in Mozart's string quintet K. 593, the Drumroll Symphony, or Beethoven's [[Piano Sonata No. 8 (Beethoven)|Pathetique piano sonata Op. 13]].

Monothematic expositions

It is not necessarily the case that the move to the dominant key in the exposition is marked by a new theme. Haydn in particular was fond of simply repeating the opening theme, often in a truncated or otherwise altered form. Mozart, despite his prodigious melodic gift, also occasionally wrote such expositions, for instance in the piano sonata K. 570 or the string quintet K. 593. Such expositions are often called monothematic. This term is usually a misnomer when applied to a sonata form movement, since "monothematic" expositions often include other themes later on in the second subject group. Only on occasion (for example, in Haydn's string quartet Op. 50 no. 1) did composers perform the tour de force of writing a complete sonata exposition with just one theme.

The monothematic exposition illustrates a general point made by Rosen about the Classical sonata form: the crucial element of the exposition is that the move to the dominant be dramatized in some way. Using a new theme was a very common way to achieve this effect, but other resources (changes in texture, salient cadences, etc.) were also available.

Modulation to keys other than the dominant

The key of the second subject may be something other than the dominant or the relative major. About halfway through his career, Ludwig van Beethoven began to experiment with new keys for the second subject group. These keys likewise move upward along the circle of fifths, but three or four fifths instead of just one. Thus,the second subject of the Waldstein sonata for piano is in E major, fourth fifths higher (C --> G --> D --> A --> E) than the tonic key of C. The Hammerklavier sonata Op. 106 moves three fifths higher (Bb --> F --> C --> G).

It is a open question why Beethoven never modulated just two fifths higher, a major second; possibly this is because it might be perceived as a crude stepwise modulation. (For a modern criticism of such modulations, see the discussion of the "truck driver's gear change" in Modulation (music).)

Modulations within the first subject group

The first subject group need not be entirely in the tonic key. In the more complex sonata expositions there can be brief modulations to fairly remote keys, followed by reassertion of the tonic. A vivid example is Mozart's String quintet in C, K. 515, which visits C minor, Db major, and D major before finally moving to the dominant of G major.

The three-key exposition

In the early part of Beethoven's career, he favored for his grander works a kind of exposition in which the exposition dwells on a third key before finally moving to the dominant. For example, in the early major-key piano sonatas this intermediate key is the dominant minor (Op. 2, no. 2), the supertonic minor (Op. 2, no. 3), and the relative minor (Op. 10, no. 3). Later, Beethoven used the supertonic major (Op. 14, no. 1, Op. 22), which is only a mild sort of three-key exposition, since the supertonic major is simply is the dominant of the dominant, and commonly arises in any event as part of modulation.

Beethoven ultimately abandoned the three-key principle, as he came to adopt a tighter conception of sonata form. Franz Schubert also used three-key expositions in many of his sonatas.

Sonata form in the Romantic era

In the Romantic era, the formal outline of a sonata was in terms of "themes" or groups of themes, each of which had a function in the progress of the music. By requiring that harmony move with the themes, this formal plan imposed a form of discipline on composers, and also allowed audiences to feel where the music was by following the appearance of recognizable melodies. The important trends in the Romantic sonata were driven by more extended harmonic movement, the desire to combine poetical expression and academic rigour, which were seen as being in tension with each other, and the focus on thematic development becoming central to the conception of a first movement.

As the 19th Century progressed, the complexity of sonata form grew, as new ways of moving through the harmony of a work were introduced by Johannes Brahms and Franz Liszt. Instead of focusing exclusively on keys related by the circle of fifths, they used movement along circles based on minor or major triads. Following the trend established by Beethoven, the focus became more and more on the development section. This was in line with the Romantic comparison of music to poetry. Poetic terms, such as "rhapsody" and "recital" and "tone poem" entered music, and increasingly musicians felt that they should not take the repeats in symphonies because there was no point. This changed their interpretation of previous sonata forms.

The final quartets of Beethoven also had an effect on the layout of "sonata" works, in that gradually it became more and more common to have all of the movements of a work be in "sonata-allegro" form. While Charles Rosen has argued that, properly understood, this was always the case, in the 19th and early 20th century, it came to mean specifically the use of the academically layed out first movement form.

The Romantic sonata form was an especially congenial mold for Brahms, who felt a strong affinity with the composers of the Classical era. Brahms adopted and extended Beethoven's practice of modulating to more remote keys in the exposition, and combined it with the use of counterpoint in the inner voices of the music. For example, his piano quintet has the first subject in F minor, but the second subject in C sharp minor, a tritone higher. In the same work, the key scheme of the recapitulation is also altered - the second subject in the recapitulation is in F-sharp minor, rather than the F minor of the first subject.

Another force acting on sonata form was the school of composers centering on Franz Liszt and Richard Wagner. They sought to integrate more roving harmonies and unprepared chords into the musical structure, in order to attain both formal coherence and a full expressive range of keys. Increasingly, themes began to have notes which were far from the original key, a procedure later labelled "extended tonality". This trend strongly influenced the next generation of composers, for instance Gustav Mahler. The first movements of several of his symphonies are described as being in sonata form, although they diverge from the above scheme quite dramatically. Some have even argued that the entirety of his first symphony (in which material from the first movement returns in the fourth movement) is meant to a massive sonata-allegro form.

As the result of these innovations, works became more sectional, composers such as Liszt and Anton Bruckner even began to include explicit pauses in works between sections. The length of sonata movements grew starting in the 1830's. The "Prize Symphony" by Lachner, a work seldom played today, had a first movement longer than any symphonic first movement by Beethoven. The length of whole works also increased correspondingly. Another area where the sonata form expanded was in the realm of "tone poems" or "symphonic poems", which would often use the first movement form, and greatly extended their length versus traditional overtures. Berlioz's "Waverly" overture is almost as long as many middle period Haydn symphonies.

One of the debates in the 19th century was over whether it was acceptable to use the layout of a poem or other literary work to structure a work of instrumental music. The compositional school focused around Liszt and Wagner - the so called "New German School" - argued in favor of literary inspiration, while another camp, centered around Schumann, Brahms, and Hanslick argued that "pure" music should follow the forms laid out by Haydn, Mozart, and Beethoven. This conflict was eventually internalized and by 1900, while the debate still raged, composers such as Richard Strauss would freely combine program with symphonic structure, such as in the work "An Heroic Life".

Sonata form in the Modern era

In the Modern period, sonata form became unhooked from its traditional harmonic basis. The works of Schoenberg, Debussy, Sibelius and Richard Strauss emphasized different scales other than the traditional major-minor scale and chords which did not establish a tonality clearly. It could be argued that by the 1930's, "sonata form" was merely a rhetorical term for any movement which stated themes, took them apart, and put them back together again. However, even composers of atonal music, such as Roger Sessions and Hartman continued to use outlines which clearly pointed back to the practice of Beethoven and Haydn, even if the method and style were quite different. At the same time, composers such as Sergei Prokofiev, Benjamin Britten and Dmitri Shostakovich revived the idea of a sonata form by more complex and extended use of tonality.

In more recent times, Minimalism has searched for new ways to develop form, and new outlines which, again, while not being based on the same harmonic plan as the Classical sonata, are clearly related to it. An example is Aaron Jay Kearnis's Symphony In Waves from the early 1990's.

Sonata form and other musical forms

Sonata form shares characteristics with both binary form and ternary form. It terms of key relationships, it is very like binary form, with a first half moving from the home key to the dominant and the second half moving back again (this is why sonata form is sometimes known as compound binary form); in other ways it is very like ternary form, being divided into three sections, the first (exposition) of a particular character, the second (development) in contrast to it, the third section (recapitulation) the same as the first.




Two works by Charles Rosen have helped define the modern conception of sonata form: The Classical Style: Haydn, Mozart, Beethoven (2nd ed. 1997; New York: Norton) and Sonata Forms (1982; New York: Norton).