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

Sonata form can be understood as a complex manifestation of a harmonically open, that is also . Due to its popularity and intricacy, sonata form has developed its own set of terms to help capture its multiple formal components. At the largest level, the form is as follows in Example 1, and each of those large levels is further sub-divided as shown in example 2.

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


Exposition is the term given to a sonata form’s first . The term helps capture the idea that the section is responsible for exposing the main thematic material of the work. In general terms, the exposition can be described as containing a main section in the tonic key, a contrasting section in a non-tonic key, a transition that separates those two sections, and the entire exposition usually ends with a (typically of the large variety). This is summarized in Example 3.

Each of those sections have specific names:

  • Primary Theme – P (main section)
  • Transition – Tr (connective section)
  • Secondary Theme – S (contrasting section)
  • Closing Section – C (suffix)
Example 3. Standard formal layout of a sonata exposition.

On the whole, the exposition is a relatively stable part of the form. The primary (P) and secondary (S) themes are expected to be highly stable though the transition between them is unstable. Because it’s a suffix, the closing section is expected to be a very stable part of the form.

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.



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 avoids complete thematic statements in favor of passages, chromaticism & modulation, and partial thematic statements. As the name implies, the development may also “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 that are quite long. 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 (either small or large) that helps to prepare the return of the primary theme in the tonic at the start of the recapitulation.


The recapitulation involves the restatement (in the same order) of material from the exposition, but with the necessary adjustments so that the secondary theme and closing sections are now in the tonic. This section is akin to the middle of a rounded binary form, where the opening of the first reprise returns. Sonata recapitulations also feature a because they restate the ending of the first reprise at the end of the second reprise, this time transposed to the tonic key. The return of material in sonata form is more consistent than in binary forms that are balanced. In sonata form, you can expect that the entire secondary theme and the closing section will return in the tonic key. In order for this key change to take place, the restatement usually has to be recomposed somewhere between the primary theme and the start of the secondary theme. 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.

Details about Sonata Form Sections

Transition (Dependent vs. Independent)

The exposition’s transition between P and S takes one of two forms, either independent or dependent. The distinction concerns the transition’s melodic/motivic material and whether or not it clearly derives from P. If it is clearly derived from P, the transition is dependent and if it does not, it 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 after getting started, veer off in another direction and they typically build energy and feel relatively unstable. A dependent transition typically involves the because they initially sound 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.

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 () 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 ). This can be in either the home key or the upcoming key of S.
  2. Textural gap: A literal space between the end of the transition and the beginning of S. 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 ().
  3. Acceptance by S. A convincing feeling of starting a new section (S) will confirm the medial caesura occurred. If the textural gap led instead 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 & Essential Structural Closure (EEC & ESC)

Hepokoski and Darcy also introduced the concepts of Essential Expositional Closure (EEC) and Essential Structural Closure (ESC) in connection with sonata form. These are parallel concepts that refer the first satisfactory PAC in S that moves on to non-S material. In the exposition, this moment is called the EEC and in the recapitulation it is called the ESC. 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 Coda


It is common for sonata forms (especially the first movement of symphonic works) to have a large 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.


Sonata forms usually contain a large after the end of the second reprise called a “coda” or “tail.” As is normal for a suffix, codas 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 —just like a binary form. As is customary in sonata form, this movement is and features a 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. This first reprise is 49 measures and half of that would be measure 24.5, so S starting in m. 23 means that it’s really rather close to the middle. Expect that S will start in the middle, not the beginning and not the end of the exposition (1st reprise).

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 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 half cadence at m. 16, which also marks the beginning of the transition’s suffix.

Standing on the dominant persists from that moment until the MC at m. 22. At this time, clear MCs are very common, and this movement’s MC represents a relatively straight-forward instance. This MC is a III:HC—a half cadence in the key of III. There is no literal silence at this moment because 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 when 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 prevents 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 , 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 it being finished. For these reasons, the potential cadence point has been . 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 with the onset of C. C lasts until the end of the exposition in m. 49.

The second reprise (mm. 50–133) can easily be understood as containing two large parts after identifying the returning of the first reprise’s opening material at m. 80. This moment marks the end of the development (the equivalent of B in a rounded binary form) and the beginning of the recapitulation (the equivalent of A’ in a rounded binary form). The development is the most unstable portion of the work, due to the variety of chromatic harmonies and large sequential component. It starts by presenting the opening of P‘s material in the mediant but quickly veers off into harmonic uncertainty with the enharmonic reinterpretation of m. 57’s chord as an augmented sixth chord in the key of E minor which initiates a large-scale, descending fifths sequence when it resolves in m. 58. The is very long, four measures in this case, and its copies are stated at m. 62 and m. 66. As Caplin points out, sequences often take up substantial portions of sonata-form developments and their sequential models are often 4 or 8 measures in length. The sequence’s last chord (A7, m. 69) resolves to D minor in m. 70 and initiates a modulating that leads back to the tonic key of A minor. The key of A minor is confirmed at the half-cadential arrival at m. 74 which again elides with the onset of a suffix and contains another instance of standing on the dominant though this occurrence has more variety in its bass line than the transition’s suffix had in the exposition. 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 ), 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.

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. Those specifics will need to change in order for the ESC to be attained in the overall key of 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. Like it did in the exposition, the transition in the recapitulation also begins in the ninth measure (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 moment, where a direct correspondence occurs between the middle of the recapitulation and the second half of the exposition, is called the . This is also the moment where the of the form comes into play. Like it does in a rounded binary form with a balanced aspect, the crux in a sonata form marks the return of the tail portion of first reprise but transposed to the tonic key. In sonata forms in particular, you should expect that all of S and C will be included in the balanced return as is the case in this movement. Though S and C may be repeated in their entirety without modification, sometimes composers decide to make changes during this restatement. In this case, 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.

  1. Maria Hester Park, Sonata, Op. 7, I Allegro Spirito (.pdf, .docx). Access score and audio.

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