Secondary Dominants

A secondary dominant is a dominant seventh chord that doesn't belong to the key but resolves to a diatonic chord as if that chord were a temporary tonic. It's like adding a burst of heat before a dish - a moment of tension that makes the resolution taste stronger.

Written as V/x ("five of x"), where x is the chord being tonicised. V/V means "the dominant of the dominant."

How it works

In any key, the V chord resolves to I. A secondary dominant borrows that pull and points it at a different chord in the key.

D7 contains F# - a note outside C major. That's the spice. The F# creates a tritone that pulls strongly towards G, making the arrival feel earned.

Hear the difference

Compare a plain diatonic approach to one with a secondary dominant. Tap each to hear how the secondary dominant adds tension before the target chord.

The most common ones

Not all secondary dominants are used equally. Here are the ones you'll encounter most, ranked by how often they appear in popular music.

Hear them all

All five secondary dominant seventh chords in C major. Tap each to hear how the chromatic note creates tension.

In a progression

Secondary dominants work best when they appear just before their target chord. They're a seasoning, not the main course - use one or two per progression, not on every chord.

That completes the Chords & Progressions topic. You now know how chords are built, the main types, how they move through time, and how to bend the rules. Next up: Melody - how to create memorable, singable note sequences.