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AP® Music Theory · Unit 5 · Topic 5.1

Predominant Function: IV and ii

IV and ii are the predominant chords that sit between tonic and dominant, building tension that makes V feel earned. They share two of their three notes, which is why they function alike and can often substitute for each other.

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Predominant function is the middle step in the basic harmonic journey: tonic, then predominant, then dominant. A chord placed right before V raises tension and distance from home, so when V finally arrives, and then resolves to I, the arrival feels earned instead of sudden. IV and ii are the two chords that do this job in major keys (ii-diminished does it in minor).

IV and ii share two of their three notes, which is exactly why they behave the same way. In a major key built on scale degree 1, IV is built on scale degree 4 and contains scale degrees 4, 6, 1. ii is built on scale degree 2 and contains scale degrees 2, 4, 6. Scale degrees 4 and 6 appear in both chords, only the bottom note changes. Because they overlap this much, both chords point toward V in the same way: scale degree 4 wants to pull down to 3, and 6 wants to pull down to 5, both motions that dominant chords complete.

This shared identity is also why ii moving to IV is not a real step forward. Progressions in major keys move in one direction through function: tonic, then predominant, then dominant, then back to tonic. Since ii and IV are both predominant, sliding between them just restates the same harmonic stage without pushing toward V. The real motion happens when a predominant chord gives way to V, which is the next topic: how predominant chords connect into the dominant through the circle progression.

Key terms

Predominant function
The harmonic stage between tonic and dominant that builds tension leading toward V.
IV
The subdominant triad, built on scale degree 4, commonly used in predominant function.
ii
The supertonic triad, built on scale degree 2, commonly used in predominant function.
Shared tones
Pitches common to two chords that explain why those chords can substitute for each other.

Watch it explained

  1. How it worksHow do IV and ii both lead into V while sharing two of their three notes?
  2. Worked exampleFind the notes of ii and IV in A major and show which two pitches they share.
  3. Common mistakeWhy isn't ii moving to IV a normal step once you have already reached predominant function?

Check yourself

Your turn1 of 2
IV and ii share two of their three notes. A passage alternates between IV and ii 4 times in a row. How many total shared-note connections does the passage contain, two per alternation?

End of topic.

Next: The ii6 Chord and Predominant Bass Lines →