III. Form

Formal Sections in General

Brian Jarvis

Key Takeaways

  • Analyzing musical form involves determining the identity and function of musical spans.
  • Musical sections are either core or auxiliary.
  • Core sections are either main or contrasting.
  • Auxiliary sections are either external or connective.

Overview of Formal Sections in General

Understanding the form of a musical work typically involves breaking it down into spans of time, based on how each span is similar to and/or contrasts with other spans. These spans are then classified based on the identity of their musical material and how the section “functions” in the context of the piece. The two largest categories of formal function are core sections and auxiliary sections.[1] Example 1 below summarizes the hierarchical relationship between some of the most common section types. At the broadest level, musical sections are either core or auxiliary. Core sections are either main or contrasting, and auxiliary sections are either external or connective.

Hierarchy chart of formal sections that summarizes the lists below.
Example 1. Core versus auxiliary formal sections.

Core Sections

The core sections identified in Example 1 typically introduce and repeat a work’s primary musical content. You can think of them as the sections you might sing for someone if they asked you how the work “goes.” You can also think of core sections as containing the work’s themes, though the term “theme” can be used in a broad or specific sense. Core sections also tend to repeat, which is another reason they will often make a stronger impression on your memory.

Main Sections

Main sections are typically the first section that presents primary musical content; they are usually repeated later in the work and are characterized by a relative sense of stability.


The terms for main sections change depending upon the conventions of the genre and form (if it is a form with a name). When thinking about form in general, the main section should be called A, but within a known form, it may go by many names, including but not limited to:

Contrasting Sections

Contrasting sections are hard to generalize, since they can vary in affect and stability. In some cases, the section is perfectly stable, and it contrasts mainly because it comes second instead of first; in other cases, a contrasting section may be the most unstable section of the work.

Unstable contrasting sections may share many musical features with connective auxiliary sections (defined below). The distinction lies in whether or not it is considered a core section: contrasting sections sound like a primary place in the work, whereas connective sections sound like a place between two core sections. In cases where the line between the two is blurry, a decision can be made based on the conventions of the overall form of the piece, or multiple formal descriptors (e.g., becoming) can be used to create an accurate and unforced classification.


Formal stability is the sense of tension vs. calmness in a portion of music. A relative sense of stability in a work is a common means of delineating form, and it is an important dramatic concern for creating momentum and engaging a listener’s expectations about what might happen, given their familiarity with how other pieces in a given genre/style behave.

Common features for each might include some combination of the following, among others:

    • Stability: relatively less change, consistent or decreasing dynamic level, tonic expansions, regular hypermeter, no modulation, diatonic melody, and diatonic harmony
    • Instability: relatively more change, increasing dynamic level, extreme registers, increased chromaticism (tonicization), increased rhythmic activity, modulation, sustained dominant, sequences (especially chromatic ones), irregular hypermeter, and irregular phrase lengths

Because it’s statistically common for works to start with a stable section, an unstable contrasting section would likely sound unusual at the beginning of a work.


In terms of form in general, the first contrasting section is labeled B, and each subsequent new section receives the next letter of the alphabet (C, D, E, etc.).Within a known form, contrasting sections go by many names, including but not limited to:

Auxiliary Formal Sections

In addition to the core sections of a work, other sections may introduce, follow, or come between these core sections. These sections are called auxiliary sections, and there are two general categories: external and connective.

External Auxiliary Sections

External auxiliary sections either introduce a piece/section (prefix) or follow the generic conclusion of the piece or section (suffix). Prefixes and suffixes come in small and large varieties.


A prefix (Rothstein 1989) refers to music that comes before the generic start of a phrase or piece and tends to express a formal sense of “before the beginning.” A prefix can be described as either small or large depending on whether or not it contains a complete phrase. Large prefixes contain at least one phrase, while small prefixes don’t have complete phrases and are typically far less noticeable. Small prefixes are often nothing more than the accompaniment for a section starting before the melody begins, and they may precede any phrase in a work.

The most common type of large prefix is called an introduction. Introductions are often in a slower tempo than the rest of the work and often contain their own thematic material. Small prefixes can be found in works of most genres and eras, but large prefixes are less ubiquitous and tend to show up more often in particular genres, like the opening of a symphony. However, other genres like the piano sonata (Beethoven’s “Das Lebewohl,” Op. 81a), string quartet (Mozart’s “Dissonance” quartet), and dance forms like ragtime (Joplin, “The Entertainer”) can contain them as well.

Below are some examples:


A suffix (Rothstein 1989) refers to music that comes after the close of a phrase or piece and tends to express a formal sense of “after the end.” The distinction between large and small again concerns whether or not it contains a complete phrase. Small suffixes can be found after the close of any phrase, but the affect is quite different depending on the type of cadence they follow. After an authentic cadence, they typically project a sense of stability and closure, but after half cadences, they tend to prepare for the entrance of the upcoming section and therefore project a sense of instability. Though possible after any phrase, large suffixes typically appear in two specific locations: (1) at the very end of a piece in the form of a coda, and (2) as the closing section of a sonata form’s exposition and recapitulation (see Sonata Form). In most cases, a suffix contains musical material that is different from the phrase it follows, though that material may be derived from an earlier phrase.

Below are some examples:

  • Small Suffix:
    • Dove Shack’s “Summertime in the LBC” – After the final chorus, a small suffix (in the form of a simple accompaniment) ends the song as it fades out from 3:41 until the end.
    • Bizet, Habanera from Carmen – The B section ends just after the singer sustains a high note and cadences with the orchestra immediately after (cadence is at 2:01). After this cadence, the orchestra just repeats an accompanimental pattern a few times. The music from 2:01-2:06 is the small suffix.
  • Large Suffix:
    • Puccini, “O Mio Babbino Caro” from Gianni Schicchi – Ending: You can hear the formal ending of the aria at 1:48 with the line “O Dio, vorrei morir!” at which time the aria could have ended satisfactorily. However, an elision occurs with the strings, which play the main melody (a.k.a. ritornello) after the soloist finishes her line. Notice that the music from 1:48 to the end projects a sense of stability, as suffixes tend to do when they follow an authentic cadence.
    • End of the 1st movement of Mozart’s “Dissonance” string quartet in C major (K. 465) – This movement ends with a coda at 9:58 (large suffix at the very end of a piece). Notice that it starts after the material from the closing section of the recapitulation comes to an end. You can compare the very end of the exposition (6:12) to the very end of the recapitulation (9:28) to hear how this large suffix is added material that was not in the exposition (even though many of its motives and ideas have been heard before).
    • Brahms’s Intermezzo in A major, op. 118, no. 2 – This work is in ternary form. The A section ends at 1:28 and is followed by a suffix from then until before the B section starts at 1:57.

Connective Auxiliary Sections


Generally, a transition is a section of music that functions to connect two core sections. Transitions usually help to lead away from the piece’s main section toward a contrasting section. In particular, a transition comes between two sections where the upcoming section is not the initiation of a large-scale return (i.e., between A and B, not between B and A). Often a modulation is introduced to help prepare a section in a new key, though it is not required. A transition also plays a role in the balance of stability and instability in a work. Core sections of a work are very often stable thematic statements (relatively), but transitions typically introduce instability (and a gain in energy), which will likely be countered by the stability of the section that follows.

Like suffixes and prefixes, transitions and retransitions (discussed further below) come in “large” and “small” varieties. A transition can be described as either small or large depending on whether or not it contains a complete phrase. Large transitions contain at least one phrase, while small transitions don’t have complete phrases and are typically far less noticeable.

Near their end, transitions (and retransitions) often drive toward attaining the dominant chord of the upcoming key. Often, a suffix will begin once the dominant has been attained in a situation sometimes called “standing on the dominant” (William Caplin) or “dominant lock” (James Hepokoski and Warren Darcy).

A transition may have a clear stopping point before the next section starts, or there may be a single melodic line that fills the space between it and the upcoming section (caesura fill), or the transition my end at the onset of the new section with an elision. In more vague cases, the end of the transition and the start of the new section may be hard to pinpoint, but it is still clear that it must have happened during a particular span of time.

Transitions are commonly found in sonata forms between the primary and secondary themes and in rondo forms between the A section (refrain) and a contrasting section (episode). Small transitions are often found in ternary forms to connect the A and B sections.

Below are some examples:


A retransition is very similar to a transition, but its location and function are different. Retransitions come between two sections where the upcoming section is the initiation of a large-scale return (i.e., between B and A, not between A and B). In most cases, retransitions help to prepare the return of the piece’s main section: the return of the A section in ternary or rondo form, or the restatement of the primary theme at the onset of the recapitulation in sonata form. A retransition often drives toward attaining the dominant chord of the home key and will often prolong the dominant once attained, usually in the form of a suffix. Retransitions may have a clear half-cadential ending (possibly followed by a suffix), or they may have an elided ending that coincides with the initiation of the following section.

Below are some examples:

Further Reading
  • Rothstein, William. 1989. Phrase Rhythm in Tonal Music. New York: Schirmer.
  • Summach, Jason. 2012. “Form in Top-20 Rock Music, 1955–89.” PhD diss., Yale University.

Media Attributions

  • hierarchy_of_form_jarvis_02

  1. This particular dichotomy was introduced by Jay Summach (2012).


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