The submediant chord is the triad built on the sixth scale degree (vi in major, VI in minor). Because it shares two notes with the tonic triad, it works as a tonic substitute, resolves deceptive cadences (V-vi), and launches circle-of-fifths progressions like vi-ii-V-I.
The submediant chord is the diatonic triad built on scale degree 6. In a major key it's minor (vi), and in a minor key it's major (VI). In C major that's A-C-E; in C minor it's A♭-C-E♭.
Here's why this chord punches above its weight. The submediant shares two of its three notes with the tonic triad (scale degrees 1 and 3), so it can stand in for tonic without actually being tonic. That's the whole trick behind the deceptive cadence, where V resolves to vi instead of I and your ear gets faked out. The submediant also moonlights as a pre-dominant launcher. The progression vi-ii-V-I is the classic descending circle-of-fifths pattern, and vi is the chord that sets the whole chain in motion. So one chord, two jobs: tonic substitute when it follows V or sits between tonic chords, and progression-starter when it moves toward ii or IV.
Submediant function lives in the harmony and voice-leading portion of AP Music Theory, where you analyze chords with Roman numerals, identify cadence types, and write four-part progressions that follow functional norms. You can't correctly label a deceptive cadence without recognizing V-vi, and you can't realize a figured bass or harmonize a melody well without knowing where vi fits in the phrase (early, heading toward pre-dominants, or as the surprise ending of a deceptive resolution). It also matters for part writing. In a V-vi resolution, you typically double the third of the vi chord to avoid parallel fifths and octaves, which is exactly the kind of detail the part-writing FRQs reward.
Keep studying AP Music Theory Unit 5
Visual cheatsheet
view galleryTonic chord (Unit 4)
The submediant is the tonic's understudy. It shares scale degrees 1 and 3 with the tonic triad, so swapping vi for I keeps the harmony stable-sounding while adding color. That overlap is what makes the deceptive cadence feel like an almost-arrival.
Dominant chord (Unit 4)
V wants to resolve to I, and when it resolves to vi instead, you get a deceptive cadence. The leading tone still resolves up to scale degree 1, which is why the motion sounds smooth even though the destination is wrong. Watch your doubling here, since the third of vi gets doubled to dodge parallels.
Circle of fifths (Unit 1)
You meet the circle of fifths first as a key-signature tool, but it comes back as a progression engine. The chord roots in vi-ii-V-I fall by fifth each time, so the submediant is the on-ramp to the most reliable progression in tonal music.
Mediant chord (Unit 4)
The mediant (iii/III) is the other chord that overlaps with tonic, but it leans toward dominant function because it also shares two notes with V. The submediant leans toward tonic and pre-dominant function instead, which is why vi shows up constantly in progressions and iii is comparatively rare.
Multiple-choice questions test whether you can identify the submediant by ear and by score, label it with the correct Roman numeral (vi in major, VI in minor), and explain its function in context. Fiveable-style practice questions ask exactly the kinds of distinctions the exam loves: how vi works differently from iii as a pre-dominant, and how vi between two tonic chords differs from an inverted dominant doing the same connective job (vi substitutes for tonic; an inverted V actively pulls back toward it). On the FRQs, the submediant shows up in figured-bass realization and Roman-numeral part writing, where you may need to resolve V to vi correctly (double the third, resolve the leading tone up) and in harmonizing a melody, where vi is a strong choice for scale degree 6 or 1 in the soprano. No released FRQ prompt names the term directly, but you can't complete a part-writing question containing a deceptive resolution without it.
Both are 'tonic-adjacent' chords that share two notes with I, so students mix them up constantly. The submediant (vi/VI) sits on scale degree 6 and behaves like a tonic substitute or pre-dominant setup, which is why it appears in deceptive cadences and vi-ii-V-I progressions. The mediant (iii/III) sits on scale degree 3 and overlaps with the dominant too, so it has a weaker, more ambiguous function and shows up far less often. Quick check: vi follows V in a deceptive cadence; iii almost never does.
The submediant chord is built on scale degree 6 and is labeled vi in major keys and VI in minor keys.
It shares scale degrees 1 and 3 with the tonic triad, which is why it can substitute for tonic.
A deceptive cadence is V resolving to vi instead of I, and in four-part writing you double the third of the vi chord to avoid parallel fifths and octaves.
The submediant launches the descending circle-of-fifths progression vi-ii-V-I, moving harmony toward the pre-dominant area.
Unlike the mediant (iii), which is rare and functionally ambiguous, the submediant has clear, common jobs and appears constantly in analysis and part-writing questions.
It's the diatonic triad built on the sixth scale degree, written vi in major keys (a minor triad) and VI in minor keys (a major triad). In C major it's A-C-E; in C minor it's A♭-C-E♭.
Both, depending on the key. In major keys the submediant is a minor triad, so it's lowercase vi. In minor keys it's a major triad built on lowered scale degree 6, so it's uppercase VI.
No, but it's the closest substitute. The submediant shares two notes with the tonic triad, so it can stand in for tonic (most famously in the deceptive cadence V-vi), but it never gives the full sense of arrival that I does.
The submediant (vi) is on scale degree 6 and the mediant (iii) is on scale degree 3. Both share two notes with tonic, but vi functions as a tonic substitute and pre-dominant launcher, while iii also overlaps with V, making its function weaker and its use much rarer.
A deceptive cadence happens when V resolves to vi instead of the expected I. The leading tone still resolves up to scale degree 1, and you double the third of the vi chord in four-part writing to avoid parallel fifths and octaves.
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