Leading-tone seventh chords are seventh chords built on scale degree 7 of a diatonic scale, written vii°7 (fully diminished) or viiø7 (half-diminished). In AP Music Theory, they have two functions: substituting for the V or V7 chord, or prolonging the tonic when placed between two tonic chords with stepwise voice leading.
A leading-tone seventh chord is a seventh chord stacked on the seventh scale degree, the leading tone. It comes in two flavors. The fully diminished seventh (vii°7) has all minor thirds between its notes and shows up naturally in minor keys (and as a borrowed chord in major). The half-diminished seventh (viiø7) has a diminished triad plus a minor seventh and is the diatonic version in major keys.
The CED (PIT-4.A.11) gives these chords exactly two jobs. First, they can substitute for V or V7 as part of the dominant function, because they share the leading tone and the dissonant pull toward tonic. Second, when placed between two tonic chords, they prolong the tonic while letting every voice (especially the bass) move by step. That second job is why this term lives in Topic 4.5 on inverted seventh chords. Per PIT-4.A.10, inverted seventh chords exist to give the bass a melodic, stepwise quality, and a vii°7 in inversion between I chords is the textbook example.
This term sits in Unit 4: Harmony and Voice Leading I, specifically Topic 4.5 (Voice Leading with Seventh Chords in Inversions), supporting learning objective 4.5.A: identifying and applying 18th-century voice-leading procedures through score analysis, error detection, writing exercises, and contextual listening. Leading-tone seventh chords are where two big Unit 4 ideas collide. They test whether you understand harmonic function (dominant vs. tonic prolongation) and whether you can execute smooth, stepwise voice leading. If you can explain why a vii°7 between two I chords isn't really 'leaving' the tonic, you understand functional harmony at the level the exam wants.
Keep studying AP Music Theory Unit 4
Visual cheatsheet
view galleryVoice Leading (Unit 4)
Leading-tone seventh chords are basically a voice-leading machine. Every note in vii°7 sits a step away from a note in the tonic triad, so each voice can resolve by step. That's why the CED pairs this chord with smooth, no-leap voice leading into and out of inversions.
Stepwise Motion (Unit 4)
PIT-4.A.10 says inverted seventh chords exist to give the bass a melodic, stepwise quality. An inverted vii°7 between two tonic chords is the classic case, letting the bass walk by step instead of jumping around.
Parallel fifths and Parallel Octaves (Unit 4)
Part-writing with leading-tone sevenths is a favorite spot for error-detection questions. Resolving the chord carelessly can produce parallel fifths, so the exam expects you to resolve the tendency tones (leading tone up, chordal seventh down) without breaking the 18th-century rules.
Tonic (Unit 1)
The whole identity of this chord is its gravitational pull toward tonic. Every dissonance in vii°7 points at a tonic-triad note, which is exactly why it can sit between two I chords and feel like the tonic never left.
Expect multiple-choice questions that ask you to identify a leading-tone seventh chord from notation or Roman numerals, name its two possible functions (dominant substitute or tonic prolongation), and explain how its inversions affect voice leading between tonic chords. Practice questions on this term ask things like 'What are the two possible functions of leading-tone seventh chords?' and how inverting vii°7 or viiø7 between two tonic chords shapes the voice leading. In the part-writing FRQs, you may need to realize a figured bass or Roman numeral progression that includes vii°7 in inversion. The graders are checking that you resolve the leading tone up to tonic, resolve the chordal seventh down by step, and avoid parallel fifths and octaves.
Both chords have dominant function and contain the leading tone, but they aren't the same chord. V7 is built on scale degree 5 and includes the actual dominant note in the bass position; vii°7 and viiø7 are built on scale degree 7 and have no root-position dominant pitch at all. Think of the leading-tone seventh as V7 with its root chopped off and a new dissonance added on top. That's exactly why the CED says it can 'substitute for' V7, and also why it does something V7 doesn't usually do: sit between two tonic chords purely to prolong the tonic.
Leading-tone seventh chords are built on scale degree 7 and come in two types: vii°7 (fully diminished) and viiø7 (half-diminished).
Per the CED, they have exactly two functions: substituting for the V or V7 chord as part of the dominant, or prolonging the tonic when placed between two tonic chords.
When used in inversion between tonic chords, they let the bass and upper voices move by step, which is the whole point of Topic 4.5's focus on inverted seventh chords.
Resolve the tendency tones correctly: the leading tone moves up to tonic and the chordal seventh resolves down by step.
Sloppy resolution of vii°7 is a common source of parallel fifths, so error-detection questions love to hide mistakes here.
viiø7 is the diatonic version in major keys; vii°7 occurs naturally in minor keys.
They're seventh chords built on the seventh scale degree, written vii°7 (fully diminished) or viiø7 (half-diminished). On the AP exam, they either substitute for the V/V7 chord or prolong the tonic between two tonic chords with stepwise voice leading.
Dominant substitution and tonic prolongation. It can stand in for V or V7 because it shares the leading tone, or it can sit between two tonic chords so the voices, especially the bass, move smoothly by step while the tonic is prolonged.
No. V7 is built on scale degree 5, while vii°7 is built on scale degree 7. They share dominant function and the leading tone, which is why vii°7 can substitute for V7, but they are different chords with different Roman numerals and different bass notes.
vii°7 is fully diminished (all minor thirds, including a diminished seventh) and occurs diatonically in minor keys. viiø7 is half-diminished (diminished triad plus a minor seventh) and is the diatonic version in major keys.
Functionally, no. The CED treats a leading-tone seventh placed between two tonic chords as tonic prolongation, not a real harmonic departure. The chord is there to keep the voice leading stepwise while the tonic stays in control.
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