How do the IV and ii chords prepare the dominant, and how do we add them to a phrase?
Topic 5.1 Adding Predominant Function IV (iv) and ii (ii diminished): use the subdominant and supertonic chords to prepare the dominant and part-write them smoothly.
A focused answer to AP Music Theory Topic 5.1, covering predominant function, the IV (iv) and ii (ii diminished) chords, how they lead to the dominant, the use of ii6 and first-inversion predominants, and smooth part-writing, with a worked predominant progression.
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What this topic is asking
The College Board (Topic 5.1) wants you to use the predominant chords, the subdominant IV (iv) and the supertonic ii (ii diminished in minor), to prepare the dominant, and to part-write them smoothly, often in first inversion (ii6).
What a predominant does
Predominants sit between tonic and dominant in the functional cycle. Using one lengthens and strengthens the approach to the cadence, which is why phrases so often run I to IV (or ii) to V to I.
IV and ii, and the first-inversion ii6
Choosing IV or ii is largely a matter of the bass line and voice leading you want. IV gives a strong subdominant bass; ii6 gives a stepwise approach to V. Both are idiomatic.
Why predominants strengthen a cadence
The central idea is that a strong cadence is built by preparing the dominant, not just arriving on it. A bare V to I works, but inserting a predominant first lets the harmony build tension in stages: the tonic is left, the predominant leans toward the dominant, the dominant strains back to the tonic, and the tonic resolves. The shared scale degree 4 is the engine, because it is the chordal seventh waiting to happen in V7 and the note that drives the predominant forward. Using ii6 in particular gives the bass a smooth, stepwise walk into the dominant, which sounds more polished than a leap. Mastering predominants turns a two-chord cadence into a full functional phrase and is the foundation for the richer progressions in the rest of Unit 5.
Part-writing a predominant
To add a predominant, choose IV or ii (often ii6), spell it, then connect from the tonic by keeping common tones and moving other voices by step, and connect to the dominant the same way, checking for parallels and resolving any tendency tones.
Try this
Q1. Which scale degree do both IV and ii contain, making them predominants? [1 point]
- Cue. Scale degree 4 (the subdominant note); it drives the predominant toward the dominant.
Q2. Why is the supertonic often used as ii6 rather than in root position? [2 points]
- Cue. First inversion puts scale degree 4 in the bass, giving a smooth stepwise bass into V; in minor it also softens the diminished supertonic triad.
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2021 (style)1 marksSection I (multiple choice, written). Which pair of chords both function as predominants leading to V? (A) I and vi (B) IV and ii (C) V and vii diminished (D) iii and IShow worked answer →
The correct answer is (B) IV and ii.
Predominant chords prepare the dominant. The subdominant (IV) and the supertonic (ii, or ii diminished in minor) are the two standard predominants; both contain scale degree 4 and move smoothly to V.
(A) I and vi are tonic-function chords. (C) V and vii diminished are dominant-function chords. (D) iii is rarely a predominant and I is the tonic. The trap is choosing tonic or dominant chords; the predominants are specifically IV and ii, the chords that set up the dominant.
AP 2023 (style)3 marksSection II (free response, part-writing). In C major, part-write the progression I to ii6 to V, keeping smooth voice leading, and explain why ii6 is a common form of the supertonic predominant.Show worked answer →
A 3-point part-writing question.
(1 point) Spell the chords: I is C, E, G; ii is D, F, A and in first inversion ii6 has F in the bass; V is G, B, D.
(1 point) Voice them smoothly, for example I (bass C, with E and G above), ii6 (bass F, with A, D and a doubled note above), V (bass G, with B and D above), keeping common tones and stepwise motion in the upper voices.
(1 point) ii6 is common because putting the third (F) in the bass gives a smooth, stepwise bass into V and lets the bass approach the dominant by step; first inversion also softens the supertonic and avoids awkward leaps.
Markers reward smooth voice leading, correct spelling and inversion of ii6, and explaining that the first inversion improves the bass line into the dominant.
Related dot points
- Topic 4.3 Harmonic Progression, Functional Harmony, and Cadences: explain tonic, predominant and dominant function, the normal direction of progressions, and the four cadence types.
A focused answer to AP Music Theory Topic 4.3, covering functional harmony (tonic, predominant, dominant), the normal flow tonic to predominant to dominant to tonic, and the four cadences (perfect authentic, imperfect authentic, half, plagal, with the deceptive cadence), with a worked cadence analysis.
- Topic 5.2 The vi (VI) Chord: use the submediant as a tonic substitute and as the goal of a deceptive cadence, and part-write V to vi correctly.
A focused answer to AP Music Theory Topic 5.2, covering the submediant vi (VI) as a tonic substitute, its role in the deceptive cadence V to vi, the special doubling needed to avoid parallels in V to vi, and its use to extend a phrase, with a worked deceptive resolution.
- Topic 5.3 Predominant Seventh Chords: use ii7 (ii diminished 7) and IV7 as predominant sevenths and resolve their chordal sevenths down by step into the dominant.
A focused answer to AP Music Theory Topic 5.3, covering the predominant sevenths ii7 (ii diminished 7 in minor) and IV7, how the chordal seventh resolves down by step into the dominant, the popular ii6/5 voicing, and smooth part-writing, with a worked resolution.
- Topic 5.5 Cadences and Predominant Function: build complete cadential progressions with predominants and harmonise a given melody so it cadences correctly.
A focused answer to AP Music Theory Topic 5.5, covering full cadential progressions that include a predominant (such as I, IV or ii, V, I), how the predominant strengthens the approach to the cadence, and how to harmonise a given melody so the cadence lands correctly, with a worked harmonisation.
- Topic 4.2 SATB Voice Leading: apply the rules of range, spacing, doubling, smooth motion and tendency-tone resolution when writing four-part harmony.
A focused answer to AP Music Theory Topic 4.2, covering the four-voice ranges, the spacing rule (no more than an octave between adjacent upper voices), doubling guidelines, the ban on parallels and voice crossing, and resolving the leading tone and tendency tones, with a worked voicing.
Sources & how we know this
- AP Music Theory Course and Exam Description — College Board (2024)