III. Form

Sonata Form

Brian Jarvis

Key Takeaways

  • Sonata form is a complex manifestation of a harmonically open, rounded binary form that is also balanced.
  • The first reprise is called the exposition, and the second reprise contains the development and recapitulation.
  • The exposition has two core sections in different keys called the primary theme and secondary theme.
  • The primary and secondary themes are separated by a transition.
  • The secondary theme is typically followed by a large suffix called the closing section.
  • The development and recapitulation may have a retransition between them.
  • The recapitulation’s secondary theme should be in the overall tonic key.
  • The sonata form proper may be preceded by an introduction or followed by a coda.

Chapter Playlist

At the largest level, the form is as follows in Example 1, and each of those large levels is further subdivided, as shown in example 2.

Example 1. Sonata form at the largest level.
Example 2. Standard formal layout of a complete sonata form.


Due to its popularity and intricacy, sonata form has developed its own set of terms to help capture its multiple formal components, but these components share properties with other formal sections (see Formal Sections in General). The sonata form’s first reprise is called the “exposition,” because it exposes the main thematic material of the work. The exposition can be further broken down into four sections with specific names:

  • Primary Theme (P): the main section, in the tonic key; concludes with a cadence in the tonic key
  • Transition (TR): the connective section; concludes with the medial caesura
  • Secondary Theme (S): the contrasting section, in a non-tonic key (typically V for major-mode pieces and III for minor-mode pieces); concludes with the essential expositional cadence
  • Closing Area (C): a large suffix in the non-tonic key.
Example 3. Standard formal layout of a sonata exposition.

On the whole, the exposition is a relatively stable part of the form. P, S, and C are all typically very stable areas; only TR is unstable.

In the exposition, expect the secondary theme to start and end in a non-tonic key. In major-key sonatas, this tends to be the dominant (V), and in minor-key sonatas, this is usually the mediant (III) or the minor dominant (v). These keys are very common in the 18th and 19th centuries, but other options also occur in the 19th century.

Dependent and Independent Transitions

The exposition’s transition between P and S takes one of two forms, depending on whether the transition’s melodic/motivic material clearly derives from P: if it does, the transition is dependent, and if it doesn’t, the transition is independent. An independent transition is usually easier to locate because it sounds like something new instead of a continuation of P. Dependent transitions might begin like a restatement of P but veer off in another direction after getting started, and they typically build energy and feel relatively unstable. A dependent transition typically involves the process of becoming because it initially sounds like P is ongoing, but as it continues, its transitional function emerges without clear delineation between the two. Another type of dependent transition can occur when P‘s suffix doesn’t come to a clear end and instead evolves into a transition through the process of becoming. However, becoming is such a common aspect of dependent transitions in sonata form that most analysts don’t bother labeling it as such.


The development is a large, unstable section. Like other unstable sections (e.g., B in rounded binary form and C in sonata rondo), the development typically favors sequential passages, chromaticism and modulation, and partial (rather than complete) thematic statements. As the name implies, the development may “develop” material from the exposition, but this is not a requirement, as the development may also introduce its own material.

Developments often explore multiple key areas through modulation or extended tonicizations. The sequential passages in developments often involve models that are quite long, often four to eight measures. For example, in the development of the first movement of Mozart’s Piano Sonata in A minor, K. 310, discussed in the analysis example below, a four-measure sequential model is used. Sequences make up such a substantial portion of Classic-era sonata developments that William Caplin suggests focusing on them when determining their overall structure. He thinks of each sequential passage, from its model to its eventual half cadence, as a “core”; suggests the possibility of multiple cores (usually only two); and describes the music between the beginning of the development to the first core as the “pre-core.”

Because developments explore non-tonic keys, they typically end with a retransition (either small or large) that helps to prepare the return of the primary theme in the tonic at the start of the recapitulation. The development often ends with a medial-caesura effect that marks a clear dividing line between the development and recapitulation. But this boundary can be less clear as well and even involve an elision, and in some cases, P starts over a dominant pedal, making it hard to hear as a clear point of initiation.


The recapitulation involves the restatement of material from the exposition, but with the necessary adjustments so that the secondary theme and closing sections are now in the tonic. In order for this key change to take place, this restatement usually has to be recomposed somewhere between the primary theme and the start of the secondary theme (creating a crux). The changes often take place during the transition, but it can also happen during the primary theme. If the exposition’s transition ended with a half cadence in the original key (e.g., Mozart, Symphony no. 25, i), then the recapitulation can actually be restated in full without changes, and the secondary theme can simply start in the tonic key with no other required changes. But often, composers decide to make changes during this restatement.

Similarity to Binary Form

Sonata form can be understood as a complex manifestation of a harmonically open, rounded binary form that is also balanced. In both forms, the opening of the first reprise returns in the middle of the second reprise (A′ in binary form; the recapitulation in sonata form), after a contrasting section (B in binary form; the development in sonata form).

Sonata recapitulations also feature a balanced aspect because they restate the ending of the first reprise at the end of the second reprise, this time transposed to the tonic key, necessitating a crux. However, the return of material in sonata form is more consistent than in binary forms that are balanced. In sonata forms in particular, you should expect that all of S and C will be included in the balanced return.


Additional Sonata Terminology: MC, EEC, ESC

Example 5. Location of Medial Caesura (MC), Essential Expositional Closure (EEC), and Essential Structural Closure (ESC).


Medial Caesura (MC)

The medial caesura is a term introduced by James Hepokoski and Warren Darcy that refers to a common phenomenon in late 18th-century sonatas where a mid-expositional break (caesura) occurs between the end of the transition and the beginning of the secondary theme. While Mozart is an exemplary champion of this technique, it is also used by earlier, later, and contemporaneous composers.

As Mark Richards explains, a “medial caesura complex” has three stages:

  1. Harmonic preparation: Occurs at the end of the transition and is most commonly a half cadence (often followed by a suffix, particularly a dominant pedal). This can be in either the home key or the upcoming key of S.
  2. Textural gap: A literal space (caesura) between the end of the transition and the beginning of S. The caesura may be preceded by a series of “hammer blows”—repeated emphatic chords. In many cases, only rests occur during this gap, but just as often, the gap is filled with a single voice that helps to bridge the gap between the two sections (caesura fill).
  3. Acceptance by S. A convincing feeling of starting a new section (S) will confirm that the medial caesura occurred. If the textural gap instead led back to material from the transition and it felt as though the secondary theme never really started, then a true medial caesura would not have occurred because the third stage was missing.

Both the exposition and recapitulation can contain a medial caesura, though they may be different because the transition is often recomposed in the recapitulation.


Essential Expositional Closure (EEC) and Essential Structural Closure (ESC)

Hepokoski and Darcy’s parallel concepts of Essential Expositional Closure (EEC) and Essential Structural Closure (ESC) refer to the first satisfactory perfect authentic cadence (PAC) in S that moves on to non-S material—this moment is called the EEC in the exposition and the ESC in the recapitulation. In both situations, this moment determines the end of S and therefore the onset of C. The harmonic goal of the exposition is to establish a new key and produce a PAC in that key, and the EEC marks that occasion. The music after the EEC, the closing section (C), was not necessary for reaching this goal and is therefore an auxiliary section of the exposition, a suffix. The same situation occurs in the recapitulation. The harmonic goal of the recapitulation is that the material from the second half of the exposition is restated in the overall tonic key and that a PAC occurs to confirm that key (ESC).


External Auxiliary Sections: Introduction and Closing Area


It is common for sonata forms (especially the first movement of symphonic works) to have a large prefix known as an introduction, or slow introduction. Introductions often contain musical material not found in the rest of the work (in the 18th century in particular). The tempo is usually significantly slower than the tempo of the sonata form proper. In many cases, the distinction between the end of the introduction and the beginning of the sonata form is quite clear, because the tempo changes abruptly when the sonata form proper begins.

Closing area

Sonata forms usually contain a large suffix after the end of the second reprise called a “closing area,” “coda,” or “tail.” As is normal for a suffix, closing sections are a stable aspect of the form, but particularly long codas might contain unstable portions. Codas may also revisit material from the rest of the work.

Sonata Form Analysis Example

EXAMPLE 6. Mozart, Piano Sonata in A minor, K 310, 1st movement. Click to see PDF score.

The first movement of Mozart’s sonata in A minor, K. 310 (1778) is a relatively clear example of a late 18th-century sonata form. As indicated by the repeat signs at mm. 49–50 and m. 133, the form has two reprises—just like a binary form. As is customary in sonata form, this movement is rounded and features a balanced aspect.

Determining the location of a sonata form’s two core sections (P and S) is an efficient approach for starting a formal analysis of the first reprise. The primary theme (P) begins in m. 1 in the key of A minor (i), and the secondary theme (S) begins in m. 23 in the key of C major (III). It’s expected that S will start somewhere around the middle of the first reprise, and that is indeed what we find: this first reprise is 49 measures, half of which is 24.5, so S starting in m. 23 puts it quite close to the middle.

Determining the location of the Tr between P and S is a more subtle task. The end of Tr is easy to identify—it’s right before S—but its beginning requires a more detailed investigation. In this case, the transition is  dependent, so at first it actually just sounds like P is continuing. Tr starts in m. 9 with a repetition of P‘s basic idea, but it starts to change soon after that, in m. 12. At that point, a harmonically unstable passage begins as it modulates to the relative key of C major (III). The tonic of the new key is most clearly established with the elided half cadence at m. 16, which also marks the beginning of the transition’s suffix.

Dominant lock persists from that moment until the MC at m. 22. In the sonata-form movements of this era, clear MCs are very common, and this movement’s MC represents a relatively straightforward instance. This MC is a III:HC—a half cadence in the key of III. There is no literal silence at this moment because caesura fill covers the space, with three eighth notes that lead to the initiation of S at measure 23. There is, however, a clear gap in texture in m. 22, as the transition finishes and S starts in the following measure. Notice also that the transition’s suffix is actually implying that the key is C minor, not C major, due to the presence of E♭s. The implication of a minor key here adds an aspect of drama to the end of the transition, and consequently an element of surprise, as S ends up being in the major mode when its preparation suggested otherwise. (Mozart doesn’t employ this technique very often, but it’s actually pretty common in Beethoven’s music.)

Remember that the harmonic goal at the end of the exposition is the EEC: the first PAC in S that moves on to non-S material. In this movement, and in many of his works, Mozart seems to be playing a sort of game with the exact location of this all-important moment. There is a clear attempt at a PAC in m. 35, but Mozart does two things that prevent it from functioning as the EEC. The first is that he withholds the local tonic in the melody, even though the trill in the previous measure suggests that the next note would have been C. Instead, the melody rests on the downbeat, and a stream of sixteenth notes start an octave higher. The second issue is that those sixteenth notes in m. 35 seem very strongly related to S‘s melodic/motivic content, which gives the impression that S is ongoing instead of being finished. For these reasons, the potential cadence point has been evaded. Mozart then continues this game by setting up another attempt at the cadence in m. 40—this time, it’s the bass voice that’s omitted at the cadence, and again S-based material continues afterward. The actual EEC only arrives in m. 45, and it elides with the onset of C. C lasts until the end of the exposition in m. 49.

The boundary between the development and recapitulation can be identified within the second reprise (mm. 50–133) by locating the return of exposition material in the tonic key. This occurs at m. 80. The development is the most unstable portion of the work, due to the variety of chromatic harmonies and sequences. It starts by presenting the opening of P in the mediant but quickly veers off into harmonic uncertainty: the apparent V7 in m. 57 is reinterpreted as an augmented sixth chord in E minor, which initiates a large-scale descending fifths sequence when it resolves in m. 58. The sequential model is very long, four measures in this case, and its copies are stated at m. 62 and m. 66. The sequence’s last chord (A7, m. 69) resolves to D minor in m. 70 and initiates a modulating retransition that leads back to the tonic key of A minor. The HC at m. 74 confirms we are back in A minor. Like in the exposition, this HC elides with the onset of a suffix with dominant lock, though this occurrence has more variety in its bass line. The effect of reaching and maintaining the dominant during this passage, however, is still quite audible. This development has a clear distinction between the end of the development and the start of the recapitulation due to the medial-caesura effect that occurs in m. 79 (notice also the chromatic line connecting the two parts that functions as caesura fill).

As expected, the recapitulation restates most of the material from the exposition, and those materials are presented in the same order. In the exposition, S and C were in III, and the transition prepared that key by modulating and ending with a half cadence in that key. For the ESC to occur in A minor, S and C can simply be transposed from C major to A minor (making sure to account for the difference in mode), but the transition will need to be rewritten to accommodate this change. As it did in the exposition, the transition of the recapitulation begins after nine measures of P, in m. 88. This transition is still dependent upon P, but it is quite different from the exposition’s version. Notice, however, that they start to become the same again at the half cadence that ends the transition and begins its suffix (compare mm. 16–22 and mm. 97–103)—this is the crux.  Mozart expands S in m. 126 by delaying the ESC with a few fully diminished seventh chords that lead back to the dominant (m. 128), which delay the ESC until m. 129. The closing section does not include recomposition, but is simply transposed to the overall tonic key of A minor, and no coda follows.

Further Reading
  • Caplin, William Earl. 1998. Classical Form: A Theory of Formal Functions for the Instrumental Music of Haydn, Mozart, and Beethoven. New York: Oxford University Press.
  • Hepokoski, James A., and Warren Darcy. 2006. Elements of Sonata Theory: Norms, Types, and Deformations in the Late Eighteenth-Century Sonata. Oxford ; New York: Oxford University Press.
  1. Maria Hester Park, Sonata, Op. 7, I Allegro Spirito (.pdf, .docx). Access score and audio.

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