Nathaniel School of Music

How to Use Secondary Dominant Chords to Write Colourful Music

A secondary dominant is the major or dominant seventh chord built a perfect fifth above any diatonic chord except the tonic; in Bb major these are G7 to Cm, A7 to Dm, Bb7 to Eb, C7 to F and D7 to Gm, and Do-Re-Mi from The Sound of Music is built almost entirely around them.

Video lesson by Jason Zac · Intermediate · 24 min

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Key points

This lesson by Jason Zac of Nathaniel School of Music explains secondary dominant chords, which are borrowed chords from outside the key that pull strongly towards another chord in the key. It is for students who already know the chords of the major scale and want to add colour to their songwriting. The theory is then applied to Do-Re-Mi from The Sound of Music, which is in the key of Bb major.

The chords of the major scale

In Bb major the seven triads are Bb major (I), C minor (ii), D minor (iii), Eb major (IV), F major (V), G minor (vi) and A diminished (vii°). Chords I, IV and V are major, ii, iii and vi are minor, and the diminished chord is rarely used. Most songs stay within these diatonic chords, but many great songs also use chords from outside the scale. Those outside chords are usually secondary dominants.

The primary dominant

Count up a fifth from the tonic: Bb, C, D, Eb, F. The major chord on the fifth degree, F, is magnetically pulled back to Bb. Add Eb to make F7 (F A C Eb) and there are two strong pulls: A rises a semitone to Bb, and Eb falls a semitone to D. The rule is simple: find the fifth of the scale, and the V chord goes to I.

Building the secondary dominants

A secondary dominant is the dominant of a chord other than the tonic. Go up a perfect fifth from the target chord's root, play a major or dominant seventh chord there, and resolve it to the target. This makes the target chord sound like a temporary home.

The V of vii° is generally ignored, because it would resolve to a diminished chord and move from something unstable to something even less stable. Seventh chords pull especially well to their landing chord. Knowing your intervals and the circle of fifths makes finding these chords quick.

How Do-Re-Mi uses them

The melody's landing notes, meaning the long notes and the notes on beat one, are almost always chord tones. Small connecting words such as a or to fall on quick passing notes, which can even step outside the chord or the scale.

  1. Do sits on Bb, and the melody outlines the Bb major triad.
  2. Re moves to F7, the primary dominant, with the melody singing notes of the F chord.
  3. Mi returns to Bb, using D and F from the tonic chord.
  4. Fa is on F7 again, and the word run lands on G, a colourful 9th above the chord.
  5. So uses Bb7 as the V of IV, resolving to Eb. On thread the melody lands on G, a note of the Eb chord.
  6. La uses C7, the V of V, resolving to F. The melody sings E, which is outside the Bb scale, because C7 contains E.
  7. Ti uses D7, the V of vi, resolving to G minor.
  8. The ending goes through another V of IV to Eb, then F, then Bb. That IV–V–I ending is a traditional way to confirm the tonic.

How to practise

Always play a secondary dominant together with the diatonic chord it resolves to. Without the resolution it just sounds like a random jump with no path home. Practise each pair as a small cadence, and sing the roots or a simple connecting line between the two chords to train your ear. Then play through Do-Re-Mi naming each chord. Learning real songs like this teaches the sound of secondary dominants more naturally than memorising a textbook. When you compose, let the ideas come instinctively rather than forcing them.

Questions about this lesson

What is a secondary dominant chord?

It is a major or dominant seventh chord built a perfect fifth above a diatonic chord other than the tonic. It pulls towards that chord and makes it sound like a temporary home.

How do I find the secondary dominant of a chord?

Go up a perfect fifth from the target chord's root and play a major or dominant seventh chord there. For example, D is the fifth of G, so D7 is the secondary dominant of G minor in Bb major.

Why is there no secondary dominant of the vii chord?

The vii chord in a major key is diminished, so resolving to it would move from an unstable chord to an even more unstable one. For this reason it is generally left out.

What chords does Do-Re-Mi use in Bb major?

It moves between Bb and F7, then uses Bb7 to Eb, C7 to F and D7 to G minor as secondary dominants. It ends with a IV–V–I back to Bb.

Practise it

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