The development section, the second large-scale section of a sonata form, succeeds the exposition's second part. It is by far the least conventional section of the sonata. Its relatively unstable tonal and phrase-structural characteristics motivate the return to stability in the recapitulation.

That said, developments should not be understood as completely unstructured or lacking conventional schematic routines. When analyzing a development section, you should keep track of at least three types of organization, outlined below. Rarely will a development section follow these models of organization precisely. Rather, you should treat them as heuristic tools to help reveal the individuality of a composition.

Tonal organization

Development sections tend to explore subordinate keys, and especially those in the minor mode. A major key sonata will often explore the submediant, mediant, and supertonic are in the development, while a minor key development will often touch upon the subdominant and minor dominant.

Most development sections do not confirm these keys through authentic cadences, as is typical in the rest of the sonata. More often these keys are confirmed by an HC.

Near its end, a development section quite often reaches a HC in the tonic key to prepare the recapitulation. That HC is often prolonged through a "standing on the dominant"—a module we will call the "retransition."

Thematic organization

There is no single standard order in which themes are presented in the development. In theory, a composer may touch on any of the themes that were part of the exposition's thematic cycle, or even introduce new themes.

However, some thematic layouts are more common than others. Developments that are based on P and TR are far more common than those based on S and C.

As a first principle, you should analyze a development in reference to the thematic cycle of the exposition (P-TR-S-C), realizing that leaving out some exposition modules is typical.

Four modules

There are generally four modules available to a development, and not all of them will necessarily be present in a given work, though they do proceed in the order shown below. The tonal and thematic layout of a development is grafted onto these modules in a variety of ways:

(1) Optional link from the preceding retransition or the closing material. This has the feeling of preceding the "development proper."

(2) Entry or preparation zone: Usually preparatory, often anticipatory, in a piano dynamic. Often P-based, but other options are possible.

(3) Central-action zone: This is the "core" of the development and usually projects a mood of restlessness and instability. In fact, the musical techniques most associated with this section are those also associated with continuation function: sequence and fragmentation especially. The CAZ may unfold in a number of sections, which are separated by cadences.

When analyzing the CAZ you should be particularly attentive of sequence technique, in particular the D2 and A2 sequences. Most often a CAZ will establish a 2-, 4-, or 8-bar "model" that is sequenced any number of times. This model may make use of motivic material from the expositional rotation or new material.

Following a passage of fragmentation, a CAZ concludes with a HC in the tonic key.

(4) Retransition: This follows the HC. Most often it contains a "standing on the dominant" and motivically may foreshadow the primary theme in order to build anticipation for the recapitulation.