6/9 6. Harmony and Chord Progressions

A progressive guide to harmonic function, common chord progressions, cadences, and Roman-numeral analysis in tonal music.

Harmonic Function: The Three-Part Plan

Harmony is the combination and succession of chords. To understand why a progression sounds stable, directional, or tense, identify the role each chord plays within the key. This role is called harmonic function.

The three primary functions are:

Tonic, abbreviated $T$ : stability, rest, and tonal focus.
Predominant, abbreviated $PD$ : movement away from tonic and preparation for the dominant.
Dominant, abbreviated $D$ : tension that strongly seeks return to tonic.

The most common large-scale pattern is:

T \rightarrow PD \rightarrow D \rightarrow T

For example, in C major, both $I \rightarrow IV \rightarrow V \rightarrow I$ and $I \rightarrow ii^6 \rightarrow V^7 \rightarrow I$ follow this general design.

Takeaway: function describes what a chord does in context, not only what notes it contains.

and Stability

provides stability and establishes the key. The tonic chord is built on scale degree $1$ , appearing as $I$ in a major key and $i$ in a minor key.

Examples include:

C major: $I$ = C–E–G.
G major: $I$ = G–B–D.
A minor: $i$ = A–C–E.
D minor: $i$ = D–F–A.

The tonic chord can begin or end a progression, follow a dominant chord, or be prolonged. Chords such as $vi$ and $iii$ may extend tonic harmony because they share tones with the tonic triad. For example, in C major:

I \rightarrow vi \rightarrow I

\mathrm{C} \rightarrow \mathrm{Am} \rightarrow \mathrm{C}

This tonic-related motion creates variety without immediately abandoning the tonal center.

Takeaway: answers the question, “Where is home?”

and Preparation

moves away from tonic and prepares the dominant. The two most important diatonic predominant chords are $IV$ in major or $iv$ in minor, and $ii$ in major or $ii^\circ$ in minor.

In C major:

$IV$ is F–A–C.
$ii$ is D–F–A.

Common patterns include:

I \rightarrow IV \rightarrow V \rightarrow I

I \rightarrow ii \rightarrow V \rightarrow I

The first-inversion supertonic chord $ii^6$ is especially common before the dominant. In C major, $ii^6$ is D minor with F in the bass, written Dm/F. Its bass motion from scale degree $4$ to scale degree $5$ leads smoothly into the dominant:

ii^6 \rightarrow V^7 \rightarrow I

A longer progression may use tonic-related chords before the predominant:

I \rightarrow vi \rightarrow ii \rightarrow V \rightarrow I

Takeaway: creates forward motion toward dominant harmony.

and Resolution

creates the strongest expectation of resolution. The dominant chord is built on scale degree $5$ and is usually represented by $V$ in both major and minor when the is present.

Common dominant-function chords include $V$ , $V^7$ , $vii^\circ$ , and $vii^{\circ 7}$ . In C major:

$V$ is G–B–D.
$V^7$ is G–B–D–F.
$vii^\circ$ is B–D–F.

Dominant tension comes partly from . In C major, the B normally resolves upward to C, while the seventh of $G^7$ , F, commonly resolves downward to E:

B \rightarrow C

F \rightarrow E

In a minor key, scale degree $7$ is commonly raised to create a . In A minor, G becomes G $\sharp$ , producing the dominant chord E–G $\sharp$ –B and dominant seventh E–G $\sharp$ –B–D.

Takeaway: concentrates tension through and normally points back to tonic.

Common Chord Progressions

A progression becomes easier to hear when its functions are connected to familiar patterns.

Basic tonic–dominant motion

I \rightarrow V \rightarrow I

In G major, this is G $\rightarrow$ D $\rightarrow$ G: the key is established, tension is created, and the tension resolves.

Basic functional progression

I \rightarrow IV \rightarrow V \rightarrow I

In C major, this is C $\rightarrow$ F $\rightarrow$ G $\rightarrow$ C, or:

T \rightarrow PD \rightarrow D \rightarrow T

Cadential predominant pattern

I \rightarrow ii^6 \rightarrow V^7 \rightarrow I

In C major, the chords are C $\rightarrow$ Dm/F $\rightarrow$ G $^{7}$ $\rightarrow$ C.

Extended circle-of-fifths motion

I \rightarrow vi \rightarrow ii \rightarrow V \rightarrow I

In C major, this is C $\rightarrow$ Am $\rightarrow$ Dm $\rightarrow$ G $\rightarrow$ C. The roots create directed motion by descending through fifth-related relationships, or ascending by fourth.

Popular-music loop

I \rightarrow V \rightarrow vi \rightarrow IV

In C major, this is C $\rightarrow$ G $\rightarrow$ Am $\rightarrow$ F. Unlike a classical cadential pattern, this loop often avoids a final $V \rightarrow I$ resolution and repeats continuously. Interpretation should consider repetition, melody, bass, and phrase structure as well as Roman numerals.

Takeaway: the same chord symbols can support different experiences of motion depending on context and style.

Cadences and Phrase Endings

A is a point of harmonic arrival that helps organize phrases. The main introductory types differ according to the final harmonic motion and the strength of closure.

: $V \rightarrow I$ or $V^7 \rightarrow I$ . It provides dominant-to-tonic closure. A perfect generally requires both chords in root position, tonic last, and scale degree $1$ in the soprano; otherwise the is usually imperfect authentic.
Half : a phrase ends on $V$ , regardless of the preceding chord. Examples include $I \rightarrow V$ , $ii^6 \rightarrow V$ , and $IV \rightarrow V$ . It sounds open or incomplete.
Plagal : $IV \rightarrow I$ . It provides a gentler close because it lacks the dominant’s leading-tone tension.
Deceptive : $V \rightarrow vi$ in major or $V \rightarrow VI$ in minor. The dominant begins an expected but avoids the tonic, allowing the phrase to continue.

Compare the effects:

V^7 \rightarrow I \quad \text{strong resolution}

V \quad \text{open ending}

IV \rightarrow I \quad \text{gentle closure}

V \rightarrow vi \quad \text{delayed or avoided resolution}

Takeaway: type is determined by the ending of a phrase, not simply by the presence of a particular chord earlier in the phrase.

A Method for Harmonic Analysis

combines key identification, chord identification, inversion, function, and .

Establish the key. Consider the key signature, tonal center, opening and closing harmony, and accidentals such as a raised .
Identify each chord’s root and quality. In C major, C–E–G is $I$ , D–F–A is $ii$ , F–A–C is $IV$ , G–B–D–F is $V^7$ , and B–D–F is $vii^\circ$ .
Determine the inversion. A first-inversion triad is marked $^6$ , a second-inversion triad $^6_4$ , a root-position seventh chord $^7$ , and a first-inversion seventh chord $^6_5$ . D–F–A with F in the bass is $ii^6$ , not simply $ii$ .
Assign function. In a major key, $I$ , sometimes $vi$ and $iii$ , are tonic-related; $ii$ , $ii^6$ , and $IV$ are usually predominant; and $V$ , $V^7$ , and $vii^\circ$ are usually dominant.
Identify the by examining the final two or three harmonies of the phrase.

Worked example:

\mathrm{C \ | Dm/F \ | G^7 \ | C}

C is $I$ , with .
Dm/F is $ii^6$ , with .
G $^{7}$ is $V^7$ , with .
The final C is $I$ , with .
The overall pattern is $T \rightarrow PD \rightarrow D \rightarrow T$ .
The final two chords form an .

Analysis remains contextual: a chord’s usual function is a useful starting point, but the surrounding progression can change how that chord behaves.

Takeaway: analyze from broad context to detail—key, chord, inversion, function, and .