Definition
The ii–V–I progression is a common chord sequence in tonal Western music that moves from the supertonic (ii) chord to the dominant (V) chord and resolves to the tonic (I) chord. It is widely used to establish or reinforce a key center, particularly in jazz, classical, and popular music.
Overview
In the context of diatonic harmony, the progression typically involves three chords built on the second, fifth, and first degrees of a major or minor scale. In a major key, the ii chord is usually a minor seventh (ii⁷), the V chord a dominant seventh (V⁷), and the I chord a major seventh (I⁷). In minor keys, variations such as iiø⁷ (half‑diminished) or ii⁷♭5 may appear. The ii–V–I creates a strong sense of tension and release, with the V chord functioning as the primary dominant that resolves to the tonic. Its prevalence in jazz has led to extensive use of altered dominants, tritone substitutions, and extended harmonies built upon the basic framework.
Etymology/Origin
The notation “ii–V–I” employs Roman numerals to denote scale degrees, a convention that originated in 18th‑century music theory treatises for representing functional harmony. The specific identification of the ii–V–I as a distinct progression emerged in the early 20th century alongside the development of jazz harmony, where it became a foundational element of improvisational practice and composition.
Characteristics
- Functional Role: Serves as a cadential or pre‑cadential device, establishing tonal resolution.
- Chord Types: Commonly realized as ii⁷–V⁷–I⁷ in major keys; in minor keys, variations such as iiø⁷–V⁷–i⁷ are frequent.
- Voice Leading: Features smooth stepwise motion of inner voices, especially the resolution of the leading tone (scale degree 7) in the V chord to the tonic.
- Extensions and Alterations: Jazz musicians often add extensions (9th, 13th) or alter the V chord (♭9, ♯9, ♭5) to increase harmonic richness.
- Substitutions: Tritone substitution (♭II⁷ for V⁷) and secondary dominants (e.g., V⁷/ii) are employed to expand the progression.
- Common Forms: Can appear in linear (sequential) or cyclical patterns, such as ii–V–I–vi, or within longer progressions like ii–V–I–IV–V.
Related Topics
- Functional harmony
- Jazz chord–scale theory
- Circle of fifths
- Cadential formulas (perfect cadence, plagal cadence)
- Tritone substitution
- Secondary dominants
- Modal interchange
- Bebop language
This entry reflects established knowledge from music theory literature and pedagogical sources.