The supertonic chord (Roman numeral ii) is the triad built on the second scale degree. It is minor in major keys and diminished in minor keys, and it almost always functions as a predominant chord that leads to the dominant (V), most famously in the ii-V-I progression.
The supertonic chord is the triad built on scale degree 2 of a diatonic scale. Stack a third and a fifth on top of re and you get it. In a major key it comes out minor, so you label it with a lowercase Roman numeral: ii. In a minor key the same stack produces a diminished triad, labeled ii°, which is why minor-key writing usually puts it in first inversion (ii°6) to soften that unstable sound.
What makes the supertonic matter on the AP exam is its job, not just its spelling. The ii chord is the poster child of predominant function. It sits between tonic and dominant in the standard harmonic flow T → PD → D → T, and its root is a fifth above V, so ii moving to V is the same strong root motion as V moving to I. That is why ii-V-I (or ii6-V-I) shows up constantly in chorales, figured bass exercises, and the harmonization FRQ.
The supertonic lives at the heart of the AP Music Theory harmony and voice-leading units. You first meet it when building diatonic triads and assigning Roman numerals, then it becomes central once the course introduces harmonic function and chord progressions, where ii and ii6 are the standard predominant choices before a cadence. If you can't deploy the supertonic correctly, you can't write a convincing authentic cadence setup, and that skill is tested directly in part writing from Roman numerals, figured bass realization, and melodic harmonization. The exam rewards you for knowing the function logic: tonic establishes, supertonic prepares, dominant demands, tonic resolves.
Keep studying AP Music Theory Unit 5
Visual cheatsheet
view galleryPredominant Function (Unit 5)
The supertonic is the textbook predominant. Its whole job is to come after tonic-area chords and before V, setting up the dominant rather than resolving anything itself. When a question asks for a predominant, ii or ii6 is almost always a safe answer.
Dominant Chord & Authentic Cadence (Unit 4)
The supertonic gets its power from what comes next. ii moving to V is root motion down a fifth, the strongest progression in tonal music, so ii-V-I is basically two dominant-style resolutions stacked back to back. That's why ii6-V-I is the go-to authentic cadence formula in part writing.
Circle of Fifths (Units 1 & 5)
Plot ii-V-I on the circle of fifths and you'll see it's three stops in a row moving by descending fifth. Longer circle-of-fifths progressions like vi-ii-V-I are just this pattern extended, and the supertonic is the link in the chain right before the dominant.
Submediant Chord (Unit 5)
The submediant (vi) frequently hands off to the supertonic, since vi to ii is another descending-fifth move. Think of vi as extending the tonic area and ii as kicking off the predominant area; together they build the smooth vi-ii-V-I path back home.
Expect the supertonic in Roman numeral analysis multiple-choice questions, where you identify ii or ii°6 in a score or hear a ii-V-I progression in a harmonic dictation excerpt. On the free-response side, the part-writing FRQs (realizing figured bass and writing from Roman numerals) regularly include a supertonic chord, and you lose points for mishandling it, especially leaving the diminished ii° in root position in minor or creating parallel fifths moving from ii to V. The melodic harmonization FRQ rewards choosing ii or ii6 as the predominant before your cadence. The skill being tested is functional: prove you know the chord prepares V instead of resolving to I.
Both ii and IV are predominant chords, and they share two common tones (scale degrees 4 and 6), so they sound and function similarly. The difference is the root and the quality. IV is built on scale degree 4 and is major in a major key, while ii is built on scale degree 2 and is minor. In first inversion, ii6 puts scale degree 4 in the bass, so it sounds a lot like IV with extra pull toward V. If the bass is on scale degree 4, check the upper voices to tell them apart.
The supertonic chord is built on scale degree 2 and is labeled ii because it is a minor triad in major keys.
In minor keys the supertonic is a diminished triad (ii°), so it almost always appears in first inversion as ii°6.
The supertonic functions as a predominant chord, meaning it leads to the dominant (V), not directly back to tonic.
ii to V is root motion by descending fifth, the same strong motion as V to I, which makes ii-V-I one of the most common progressions in tonal music.
On part-writing and harmonization FRQs, ii6 before V is a standard, point-safe way to set up an authentic cadence.
It's the triad built on the second scale degree, labeled with the Roman numeral ii. In C major, that's D-F-A. Its main job is predominant function, leading the harmony toward the dominant chord (V).
In a major key it's minor (ii). In a minor key it's diminished (ii°), which is why minor-key part writing usually places it in first inversion as ii°6 to put a more stable interval against the bass.
No, not directly. The supertonic is a predominant, so it moves to V (or V7) first, and the dominant then resolves to tonic. Writing ii straight to I skips a step in the functional progression T → PD → D → T and will sound (and score) wrong on part-writing FRQs.
Both are predominants, but the subdominant (IV) is built on scale degree 4 and is major, while the supertonic (ii) is built on scale degree 2 and is minor. They share two notes, and ii6 even puts scale degree 4 in the bass, so check the full chord spelling before labeling.
ii6 puts scale degree 4 in the bass, which creates a smooth stepwise descent to scale degree 5 at the cadence (4 down to 5 is actually a step up or a smooth approach in the bass line). It also matches the IV-like sound composers favor before V, making ii6-V-I the classic cadence setup.
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