Secondary dominants are chords that briefly make a chord other than the tonic sound like a temporary goal. This cheat sheet helps students recognize, label, spell, and resolve applied dominant chords in tonal music. It is especially useful for Roman numeral analysis, part writing, harmonic dictation, and composition.
Students need these patterns because they explain many chromatic notes that do not belong to the main key.
Key Facts
- A secondary dominant is labeled V/x or V7/x, where x is the temporary tonicized chord within the home key.
- To build V/x, find the root of chord x, then build a major triad a perfect fifth above it.
- To build V7/x, build a dominant seventh chord a perfect fifth above x, using root, major third, perfect fifth, and minor seventh.
- In major keys, common secondary dominants include V/V, V/ii, V/iii, V/IV, and V/vi.
- In minor keys, common secondary dominants include V/V, V/iv, V/VII, V/III, and V/VI, depending on the harmonic context.
- The leading tone of the tonicized chord is usually raised with an accidental and should resolve upward by half step to the temporary tonic.
- A secondary dominant normally resolves to its target chord, so V/V resolves to V and V7/ii resolves to ii.
- A secondary dominant tonicizes a chord briefly, but it does not create a full modulation unless the new key is confirmed for a longer passage.
Vocabulary
- Secondary dominant
- A dominant-function chord that temporarily points to a diatonic chord other than the main tonic.
- Tonicization
- The brief emphasis of a chord as if it were a temporary tonic without fully changing keys.
- Applied chord
- A chord borrowed from the key of a temporary tonic and used to strengthen the arrival on that chord.
- V/x
- A Roman numeral label meaning the dominant chord of the chord shown after the slash.
- Leading tone
- A note one half step below a tonic or temporary tonic that has a strong tendency to resolve upward.
- Modulation
- A longer change of key that is confirmed by cadences or sustained harmonic activity in the new key.
Common Mistakes to Avoid
- Labeling every accidental as a secondary dominant is wrong because chromatic notes can also come from mixture, passing tones, neighbor tones, or modulation.
- Building V/x on chord x is wrong because the dominant of x is built a perfect fifth above x, not on x itself.
- Forgetting to raise the leading tone is wrong because a secondary dominant usually needs a major third that pulls strongly toward the temporary tonic.
- Calling a brief tonicization a modulation is wrong because modulation requires a more stable change of key, often supported by a cadence in the new key.
- Resolving V7/x to the wrong target chord is wrong because the slash chord tells the resolution goal, so V7/vi should resolve to vi.
Practice Questions
- 1 In C major, spell the notes of V/V and name the chord it should resolve to.
- 2 In G major, spell the notes of V7/ii and name the chord it should resolve to.
- 3 In F major, identify the Roman numeral for the chord A major when it resolves to D minor.
- 4 Explain why the progression C major, A7, D minor, G7, C major is tonicization rather than a full modulation to D minor.
Understanding Secondary Dominants & Tonicization Reference
The strongest clue is usually voice leading, not the chord label by itself. A dominant chord contains notes that want to move in particular directions. In the key of C major, D7 moving to G gives F sharp a strong pull upward to G.
The chordal seventh, C, usually moves downward to B. These two small steps create the feeling of arrival. When students hear this motion, the altered note stops seeming random.
It is part of a directed line that points toward the next chord. In four-part writing, resolve these tendency tones carefully before worrying about less urgent notes.
Work backward from a suspected applied chord. First find the chord that follows it. Then ask whether the earlier chord has the root and quality expected of that following chord's dominant.
For example, an A major chord before D minor in C major is not simply an unusual version of vi. Its C sharp belongs to the pull toward D. The same idea helps separate secondary dominants from borrowed chords.
A borrowed chord gets its color from a parallel major or minor mode. A secondary dominant gets its color from a clear resolution pattern.
Context decides the analysis. An accidental alone does not prove either one.
Inversions can hide the pattern from the eye. A secondary dominant may appear with its third, fifth, or seventh in the bass, while its function remains the same. Listen for the root movement and inspect the notes above the bass.
Seventh chords are especially useful because their seventh normally has a predictable downward resolution. A composer may delay the target with a passing note, a suspension, or a cadential decoration.
Even then, the target is often still clear over a short span. In analysis, mark the actual arrival chord rather than labeling from the bass note alone.
Tonicization is common in songs, film music, hymns, and classical phrases because it adds motion without leaving the home key for long. It often appears near a cadence or before an important phrase goal. A longer change of key has stronger evidence.
It may include several chords that support the new tonic, a new key signature, or a cadence that settles there. Students should train both their ears and their eyes. At the keyboard, play a plain progression, then insert a dominant aimed at one upcoming chord.
Notice how the added accidental creates expectation. In written work, check every altered pitch for a sensible destination. If it resolves by step into the next chord, the Roman numeral analysis is usually on solid ground.