7.1 Secondary Dominants

Borrowing a dominant

A secondary dominant is a dominant chord of a chord other than the tonic — it temporarily treats another chord as a mini-tonic. Notated V/x ('five of x'), e.g. V/V ('five of five').

Creating the chord

To build V/V in C major: the dominant of G is D major (D–F♯–A). The raised F♯ (a chromatic note) is the tell-tale sign of a secondary dominant.

Resolution

A secondary dominant resolves to its target chord as if that chord were the tonic: V/V → V, V/ii → ii, V7/IV → IV. The chromatic leading tone rises to the target's root.

Key terms

Secondary dominant

the dominant of a chord other than the tonic

Notation V/x

'five of x' — e.g., V/V, V/ii, V7/IV

V/V in C major

D major (D–F♯–A)

Tell-tale sign

a chromatic (raised) leading tone

Resolution

resolves to its target as if it were the tonic

Try an AP-style question

In C major, V/V is…

1. A major
2. D major (D–F♯–A)
3. D minor
4. G major