Authentic Cadence

An authentic cadence is a dominant-to-tonic (V-I or V7-I) progression that ends a musical phrase; it's a perfect authentic cadence (PAC) when both chords are in root position and scale degree 1 is in the soprano, and an imperfect authentic cadence (IAC) when either condition is missing.

What is the Authentic Cadence?

An authentic cadence is the V-to-I move at the end of a phrase. In tonal music (the common-practice tradition, roughly 1650-1900), every chord relates back to the tonic, and the authentic cadence is the moment that relationship gets confirmed. The dominant chord builds tension, the tonic resolves it, and the phrase feels finished.

The CED splits authentic cadences into two flavors. A perfect authentic cadence (PAC) requires V-I with both chords in root position and scale degree 1 in the soprano voice. That's the strongest possible ending in tonal music, the harmonic equivalent of a period. An imperfect authentic cadence (IAC) still goes dominant to tonic, but something weakens it. Maybe a chord is inverted, or the soprano lands on scale degree 3 or 5 instead of 1. The CED files the PAC under conclusive cadences and the IAC under inconclusive cadences, alongside half and deceptive cadences. Same progression, very different sense of closure.

Why the Authentic Cadence matters in AP Music Theory

Authentic cadences live in Unit 4: Harmony and Voice Leading I, specifically Topic 4.3 (Harmonic Progression, Functional Harmony, and Cadences). Learning objective AP Music Theory 4.3.B asks you to identify cadence types in both performed and notated music, so you need to recognize an authentic cadence by ear and on the page. It also feeds AP Music Theory 4.3.A, because the V-I motion is the clearest demonstration of harmonic function there is. Dominant function exists to pull toward tonic, and the authentic cadence is that pull paying off. Once you can spot it, you can map the function of everything leading up to it. It also matters for part writing in Topic 4.5, since dominant-function chords like V7 and the leading-tone seventh resolve into tonic with specific voice-leading rules you have to follow.

How the Authentic Cadence connects across the course

Dominant Chord (Unit 4)

The authentic cadence is the dominant chord doing its one job. V exists to resolve to I, and the cadence is where that resolution actually happens. If you understand why V wants to move to I, you understand functional harmony.

Leading Tone (Units 1 and 4)

The leading tone (scale degree 7, sitting inside the V chord) is the engine of the authentic cadence. Its half-step pull up to tonic is what makes V-I feel inevitable. In four-part writing, a leading tone in an outer voice has to resolve up to scale degree 1.

Leading-tone Seventh Chords (Unit 4)

Per PIT-4.A.11, vii°7 can substitute for V or V7 as part of the dominant function. That means a phrase can approach its cadence through a leading-tone seventh chord instead of a plain V and still land with authentic-cadence force.

Plagal Cadence (Unit 4)

The other conclusive cadence in the CED. Plagal uses IV-I instead of V-I, so it skips the leading tone entirely. That's why it sounds gentler (think the 'Amen' at the end of a hymn) while the authentic cadence sounds decisive.

Is the Authentic Cadence on the AP Music Theory exam?

Authentic cadences show up everywhere on this exam. Multiple-choice questions ask you to identify cadence types from notation or from a listening excerpt, and to distinguish a PAC from an IAC (root position plus scale degree 1 in the soprano, or it's not perfect). The big one is the bass-line harmonization FRQ. Question 7 on the 2023, 2024, and 2025 exams gave a melody and asked you to write a bass line with Roman and Arabic numerals following 18th-century voice-leading procedures. Phrases in that question are expected to close with proper cadences, and the final cadence is normally a root-position authentic cadence. You earn points by choosing V-I (or V7-I) at the phrase ending, resolving the leading tone correctly, and avoiding parallel fifths and octaves on the way in.

The Authentic Cadence vs Plagal Cadence

Both are conclusive cadences that end on tonic, so it's easy to blur them. The difference is the chord before I. An authentic cadence approaches tonic from the dominant (V-I), which includes the leading tone and its half-step pull to scale degree 1. A plagal cadence approaches from the subdominant (IV-I), with no leading tone involved, so it sounds softer. On a listening question, if the final two chords feel like 'A-men,' it's plagal; if they snap shut with real finality, it's authentic.

Key things to remember about the Authentic Cadence

• An authentic cadence is a V-I (or V7-I) progression at the end of a phrase, and it's the strongest signal of closure in tonal music.

• A perfect authentic cadence (PAC) requires both V and I in root position with scale degree 1 in the soprano; break either rule and it becomes an imperfect authentic cadence (IAC).

• The CED classifies the PAC as conclusive and the IAC as inconclusive, grouping the IAC with half and deceptive cadences.

• The leading tone inside the V chord creates the half-step pull to tonic that gives the authentic cadence its decisive sound.

• A vii°7 chord can substitute for V as part of the dominant function, so a cadence can arrive through a leading-tone seventh chord.

• On the bass-line harmonization FRQ, ending each phrase with the correct cadence, usually a root-position authentic cadence, is worth points.

Frequently asked questions about the Authentic Cadence

What is an authentic cadence in AP Music Theory?

It's a phrase ending built on the progression V-I (or V7-I), where the dominant chord resolves to the tonic. It appears in Unit 4, Topic 4.3, and it's the standard conclusive cadence of common-practice tonal music.

What's the difference between a perfect and imperfect authentic cadence?

A PAC has both V and I in root position with scale degree 1 in the soprano voice. An IAC is still V-I, but with an inverted chord or a soprano ending on scale degree 3 or 5, which weakens the sense of closure enough that the CED calls it inconclusive.

Is an authentic cadence the same as a plagal cadence?

No. An authentic cadence moves V-I and contains the leading tone, while a plagal cadence moves IV-I with no leading tone. Both end on tonic, but the authentic cadence sounds stronger and the plagal cadence sounds like a hymn's 'Amen.'

Does V7 to I count as an authentic cadence?

Yes. V7-I is an authentic cadence, and it can still be a PAC if both chords are in root position and scale degree 1 is in the soprano. The added chordal seventh just has to resolve down by step in voice leading.

Do I need authentic cadences for the AP Music Theory FRQs?

Absolutely. The bass-line harmonization question (Question 7 on the 2023, 2024, and 2025 exams) expects phrases to close with proper cadences, typically a root-position authentic cadence with the leading tone resolving up to tonic.