Sonata Form

Sonata form is the most important and widely discussed large-scale form in tonal music. It governs the first movements (and often other movements) of symphonies, string quartets, piano sonatas, and concertos from roughly 1750 to 1900. The form consists of three main sections: exposition, development, and recapitulation. The exposition introduces the thematic and tonal argument of the movement; the development works through that argument; the recapitulation resolves it.

The exposition is itself subdivided into four functional zones. The primary theme zone (P) establishes the tonic with the movement's main theme. The transition (TR) destabilizes the tonic through increased energy, sequential motion, and modulation, ending with a medial caesura — a dramatic pause that marks the arrival at the secondary key area. The secondary theme zone (S) introduces new, typically more lyrical or contrasting material in the new key (the dominant in major-key movements, the relative major in minor-key movements). The closing zone (C) confirms the secondary key with cadential material. The entire exposition is normally repeated.

The development section explores the movement's thematic material through fragmentation, sequential treatment, rapid modulation through multiple keys, and contrapuntal elaboration. It typically avoids the tonic until a retransition passage — often intensely unstable — leads back to the tonic for the recapitulation. The recapitulation restates the exposition's material but crucially brings the secondary theme zone back in the tonic key, resolving the tonal tension established in the exposition. A coda may follow, providing a final tonic confirmation. The drama of sonata form is thus a drama of tonal argument: the home key is abandoned, tested, and ultimately reclaimed.