---
title: "Leading-Tone Triad (vii°) — AP Music Theory Definition"
description: "The leading-tone triad (vii°) is the diminished triad built on scale degree 7. Learn its Roman numeral, why it's diminished, and how it resolves to I on the AP exam."
canonical: "https://fiveable.me/ap-music-theory/key-terms/leading-tone-triad"
type: "key-term"
subject: "AP Music Theory"
unit: "Unit 3"
---

# Leading-Tone Triad (vii°) — AP Music Theory Definition

## Definition

The leading-tone triad is the diminished triad built on the seventh scale degree of a key, labeled vii° (lowercase Roman numeral plus the ° symbol). When it appears in root position, it resolves directly to a root-position tonic (I) chord.

## What It Is

Build a [triad](/ap-music-theory/unit-7/tonicization-through-secondary-dominant-chords/study-guide/rLCBduMA9EmMPYSSNiwd "fv-autolink") on [scale degree](/ap-music-theory/key-terms/scale-degree "fv-autolink") 7 of a major key and you get something unusual. Every other diatonic triad is major or minor, but this one stacks two minor thirds, which makes it diminished. That's the leading-tone triad. In D major, for example, it's C#-E-G.

The label tells you everything. Per the CED's Roman numeral system (PIT-2.A.1), lowercase numerals mean minor, uppercase means major, and the ° symbol marks diminished. So vii° says "[chord](/ap-music-theory/unit-3/triad-chord-qualities-m-m-d-a/study-guide/C2Wj35yXuDEj0tYdyQcc "fv-autolink") built on scale degree 7, diminished quality" all in three characters. The chord is unstable because it contains a tritone (in D major, that's C# against G), and its root is the leading tone itself, which pulls strongly up to tonic. That pull is why the resolution rule exists. A root-position vii° resolves directly to a root-position I.

## Why It Matters

The leading-tone triad lives in **Topic 3.2 (Diatonic Chords and Roman Numerals)** in **[Unit 3](/ap-music-theory/unit-3 "fv-autolink"): Music Fundamentals III**, and it directly supports learning objective **[AP Music Theory](/ap-music-theory "fv-autolink") 3.2.A**, which asks you to identify chords by Roman numeral, quality, and bass note in both performed and notated music. Here's the thing that makes vii° worth extra attention. It's the only diminished triad among the diatonic triads of a major key, so it's the chord most likely to test whether you actually know your quality symbols or you're just guessing uppercase versus lowercase. It also carries dominant function, meaning it pushes toward tonic the same way V does, which makes it show up constantly once you start writing bass lines and four-part harmony in later units.

## Connections

### [Root Position (Unit 3)](/ap-music-theory/key-terms/root-position)

The [resolution](/ap-music-theory/key-terms/resolution "fv-autolink") rule for vii° is tied to its bass note. A root-position vii° must go straight to a root-position I, which is exactly why composers usually put vii° in first inversion instead. The inversion softens the bass motion and frees up the voice leading.

### Diatonic Chords and Roman Numerals (Unit 3)

vii° is the textbook case for the CED's chord-labeling system. Lowercase numeral plus ° equals diminished, and in a [major key](/ap-music-theory/key-terms/major-key "fv-autolink"), scale degree 7 is the only place a diminished triad occurs diatonically. If a question shows you a ° symbol on a triad in major, your brain should jump to scale degree 7.

### Eighteenth-Century Voice Leading (Units 4-7)

Once you move into part writing, vii° stops being a labeling exercise and becomes a voice-leading problem. Its tritone wants to resolve ([leading tone](/ap-music-theory/key-terms/leading-tone "fv-autolink") up to tonic, scale degree 4 down to 3), and bass-line FRQs expect you to handle that pull correctly when you harmonize a melody.

## On the AP Exam

On multiple choice, expect identification and manipulation questions. A typical stem gives you a key and the vii° chord, then alters a note. For example, in D major the leading-tone triad is C#-E-G; raise the fifth a half step to G# and the chord becomes C#-E-G#, a minor triad. You need to know the spelling cold to handle that kind of question. On the free-response side, the bass-line harmonization SAQ (like 2025 SAQ Q7) asks you to complete a bass line with Roman and Arabic numerals following eighteenth-century voice-leading procedures, and vii° is one of the chords you can deploy there, as long as you respect its resolution behavior. The skill being tested is always the same. Spell the chord correctly, label it correctly (lowercase plus °), and resolve it to tonic.

## leading-tone triad vs Dominant triad (V) and dominant seventh (V7)

Both vii° and V push toward tonic, so they share dominant function, but they're different chords. V is a major triad on scale degree 5 (uppercase, no symbol), while vii° is a diminished triad on scale degree 7 (lowercase plus °). A useful mental shortcut is that vii° contains the same three upper notes as V7, just without the root. So in D major, V7 is A-C#-E-G and vii° is C#-E-G. Same tritone, same pull to tonic, different root and different Roman numeral.

## Key Takeaways

- The leading-tone triad is built on scale degree 7 and is the only diminished triad among the diatonic triads of a major key.
- It's labeled vii°, where the lowercase numeral plus the ° symbol signals diminished quality, exactly as the CED's Roman numeral system requires.
- A root-position vii° must resolve directly to a root-position I chord, which is why the chord more often appears in first inversion in real music.
- vii° contains a tritone between the leading tone and scale degree 4, and that instability is what gives the chord its strong pull toward tonic.
- Know the spelling in any key, because MCQs love to alter one note of vii° and ask what quality results (in D major, raising the fifth of C#-E-G to G# produces a minor triad).

## FAQs

### What is the leading-tone triad in AP Music Theory?

It's the diminished triad built on the seventh scale degree of a key, labeled vii° with a lowercase Roman numeral and the ° symbol. In D major, it's spelled C#-E-G.

### Is the vii° chord major or minor?

Neither. It's diminished, made of two stacked minor thirds, which is why it gets a lowercase numeral plus the ° symbol instead of plain uppercase or lowercase.

### How is vii° different from V7?

Different root, same job. V7 is a dominant seventh on scale degree 5 (in D major, A-C#-E-G), while vii° is the diminished triad on scale degree 7 (C#-E-G). vii° is essentially V7 with the root removed, so both contain the same tritone and pull toward tonic.

### Does vii° always have to resolve to I?

When vii° is in root position, yes, it must resolve directly to a root-position I chord. That strict rule is a big reason the chord usually shows up in first inversion in eighteenth-century style writing.

### Why is the triad on scale degree 7 diminished?

Stacking diatonic thirds on scale degree 7 of a major key gives you two minor thirds, producing a tritone between the root and fifth. In D major, that's the tritone between C# and G.

## Related Study Guides

- [3.2 Diatonic Chords and Roman Numerals](/ap-music-theory/unit-3/diatonic-chords-roman-numerals/study-guide/ROGfWcFThaDu0yMJWgCE)

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