5.1 Adding Predominant Function IV (iv) and ii (ii0) to a Melodic Phrase

Predominant chords sit between tonic and dominant to build tension before a cadence. The two main predominant chords are the subdominant (IV in major, iv in minor) and the supertonic (ii in major, ii° in minor), and adding them turns a basic tonic dominant tonic phrase into the fuller tonic predominant dominant tonic (T PD D T) shape.

Predominant function is part of the harmonic vocabulary you will keep using for the rest of AP Music Theory, from later Unit 5 chords to cadences. Once you can hear where a phrase leaves tonic and prepares the dominant, labeling chords, taking dictation, and writing bass lines under a melody all get easier.

Where IV and ii Fit Before the Dominant

• Predominant chords come before the dominant and intensify the move toward a cadence, giving the order tonic-predominant-dominant-tonic (T-PD-D-T).
• The subdominant (IV in major, iv in minor) and the supertonic (ii in major, ii° in minor) are the core predominant chords.
• IV shares a common tone with the tonic (a perfect fifth below), which makes a smooth move into the predominant area.
• The ii chord often appears in first inversion (ii⁶ or ii°⁶) so the subdominant sits in the bass and reinforces predominant function.
• If a phrase uses both IV and ii, the usual order is IV then ii (IV-ii-V), which moves smoothly toward the dominant.
• When a predominant moves to V⁷, use contrary motion against the bass and keep common tones to avoid parallel fifths and octaves.

Reviewing Harmonic Function

Image from: http://openmusictheory.com/harmonicFunctions.html

Harmonic function is the role a chord plays in a phrase. In tonal music, chords group into functions:

• Tonic / tonic prolongation: I, vi, iii in major; i, VI, III in minor (the "home" area)
• Predominant: IV (iv) and ii (ii°), which prepare the dominant
• Dominant: V⁷ or vii°, which pulls back toward tonic

If you need a refresher on tonic and dominant function, see Unit 4.3.

In Unit 4 you saw that a dominant-to-tonic motion completes a phrase at a cadence, and that phrases usually start on tonic. A phrase that moves from a tonic area to a dominant-tonic cadence is a tonic-dominant-tonic (T-D-T) phrase.

The problem with staying in just two areas is balance. Too much tonic sounds static because tonic is so stable. Too much time in the dominant feels stretched, because by then your ear is already expecting resolution. Predominant chords fix this by adding a fresh stage of tension between the two.

Predominant Function

Predominant chords are named for what they do: they lead to the dominant. Just as the dominant strongly pulls toward tonic, the predominant strongly pulls toward the dominant. It is also easy to move from a tonic chord into a predominant chord.

So a phrase that was I-V-I can become I-ii-V-I or I-IV-V-I. Think of the predominant section as a preparation for the dominant. It expands the basic phrase from T-D-T to T-PD-D-T, and this fuller shape shows up more often than plain T-D-T.

The VI and III chords have their own special roles, which you can explore in 5.2 The vi (VI) Chord and 5.4 The iii (III) Chord.

If you have a keyboard nearby, play a quick I-IV-V-I. It probably sounds familiar, because that progression is everywhere in both popular and classical music.

The Subdominant Chord (IV or iv)

The subdominant chord (IV in major, iv in minor) is a very common first predominant chord. It sits a perfect fifth below the tonic, so moving down the circle of fifths takes you from tonic straight to IV.

The subdominant also allows smooth stepwise motion out of tonic, and it shares a common tone with the tonic. In F major, the I chord is F-A-C and the IV chord is B♭-D-F. Keeping the shared F lets you hold onto some tonic color while still leaving the tonic area.

When you part-write IV in root position, the root in the bass emphasizes its predominant function, which is often the cleaner choice in a major key. If you use the first-inversion IV⁶ (or iv⁶), the third of the chord moves to the bass instead, so plan your upper voices to avoid parallel perfect intervals and keep good doubling.

The Supertonic Chord (ii or ii°)

The supertonic chord (ii in major, ii° in minor) is another strong predominant option, and it adds variety so your phrases are not always I-IV-V-I. In a sense, ii works as a slightly weaker substitute for IV. You can use ii alone in the predominant section, or place it after IV to extend that section. If you use both, IV usually comes first, because ii leads more smoothly into V.

As a triad, the supertonic often appears in first inversion (ii⁶ or ii°⁶). With first inversion, the subdominant scale degree sits in the bass, which reinforces the predominant function. Doubling the third of ii⁶ or ii°⁶ puts even more weight on that subdominant pitch.

Predominant seventh chords, including ii⁷, get full treatment in 5.3 Predominant Seventh Chords. For now, just know that seventh-chord versions of the predominant chords do the same predominant job as the triads.

The ii chord is especially handy when you are heading into a V⁷, because moving directly from IV to V⁷ can be awkward to voice cleanly.

Voice Leading from the Predominant to V⁷

Contrary motion against the bass is your main tool, but there are still details to check. When a predominant chord moves to a V⁷, prepare the chordal seventh (the seventh of the V⁷) as a common tone where possible, so it does not just leap in. Because V⁷ has four different pitches, choose the predominant voicing carefully. Keep common tones when you can and use contrary motion to avoid parallel fifths and octaves.

Spotting and Voicing Predominant Chords in Analysis and Part Writing

Score Analysis: Scan for the T-PD-D-T shape. After the opening tonic area, look for IV (iv) or ii (ii°) right before the dominant. Label inversions accurately: a ii in first inversion is ii⁶, and in minor it is ii°⁶. The subdominant pitch in the bass is a strong clue that you are in the predominant area.

Contextual Listening / Dictation: Train your ear to hear the predominant as a stage of rising tension between the stable tonic and the resolution-hungry dominant. A IV often sounds open and plagal, while ii (or ii°) leans a bit more pointed toward the dominant. Hearing that "preparation" sound helps you place chords correctly in harmonic dictation.

Part Writing / Figured Bass: When you add a bass line to a given melody or realize a figured bass, plan the predominant-to-dominant move first since it is the trickiest spot. Use root-position IV when you want a strong predominant, ii⁶ when you want smoother bass motion, and contrary motion into V or V⁷ to stay clean.

Common Trap: Moving IV directly to V⁷ in four voices is where parallels sneak in. If the voicing feels clunky, try ii (or ii⁶) into V⁷ instead, and always check the outer voices for parallel fifths and octaves.

Common Misconceptions

• Misconception: Predominant chords can go anywhere in a phrase.
  Actually: They belong before the dominant. Their whole job is preparing V, so they sit in the predominant slot of T-PD-D-T.
• Misconception: IV and ii are interchangeable in any order.
  Actually: When both appear in the same predominant section, the common pattern is IV then ii before the dominant.
• Misconception: ii must be in root position.
  Actually: As a triad, the supertonic predominant is usually in first inversion (ii⁶ or ii°⁶) so the subdominant scale degree is in the bass.
• Misconception: In minor, ii is a normal predominant triad.
  Actually: In minor the supertonic triad is diminished (ii°), which is why it commonly appears in first inversion rather than root position.
• Misconception: Once you reach the dominant, voice leading is automatic.
  Actually: Moving a predominant into V⁷ still requires care: prepare the chordal seventh, keep common tones, and use contrary motion to avoid parallels.

Related AP Music Theory Guides

• 5.6 Cadential 6/4 Chords
• 5.5 Cadences and Predominant Function
• 5.7 Additional 6/4 chords
• 5.4 The iii (III) Chord
• 5.3 Predominant Seventh Chords
• 5.2 The vi (VI) Chord