Key Concepts of Secondary Dominant Chords

Why This Matters

Secondary dominants are one of the most powerful tools composers use to create harmonic motion and interest—and they're absolutely essential for any serious harmonic analysis. When you encounter a chord that seems "out of key" but resolves smoothly to a diatonic chord, you're almost certainly looking at a secondary dominant. Understanding these chords unlocks your ability to analyze everything from Bach chorales to jazz standards to contemporary pop progressions.

You're being tested on more than just identifying $V/x$ notation. Examiners want to see that you understand why secondary dominants work, how they create temporary tonal centers through tonicization, and when they cross the line into actual modulation. Don't just memorize the formula—know what harmonic principle each secondary dominant illustrates and how it functions within the larger progression.

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Defining and Notating Secondary Dominants

Secondary dominants borrow the dominant function from other keys to temporarily emphasize non-tonic chords, creating mini moments of tension and resolution within a single key.

What Makes a Chord a Secondary Dominant

• A secondary dominant is the V chord of any diatonic chord except the tonic—it "borrows" dominant function to point toward a non-tonic target
• Typically contains a chromatic alteration that creates a leading tone to the root of the target chord, generating the characteristic pull of dominant-to-tonic motion
• Creates temporary tonicization without abandoning the home key, distinguishing it from actual modulation

Roman Numeral Notation System

• Notated as V/x where x represents the chord being tonicized—read as "five of x" or "the dominant of x"
• In C major, V/ii = A major because A major is the V chord in the key of D minor (the ii chord)
• Seventh chords use V7/x notation, adding the characteristic dominant seventh tension before resolution

Identifying Secondary Dominants in Scores

• Look for major triads or dominant sevenths resolving to non-tonic chords—these are your primary suspects
• Check for chromatic alterations that create leading tones; the raised note typically sits a half-step below the root of the target chord
• Analyze harmonic context to confirm the chord functions as a dominant rather than a borrowed chord or chromatic passing harmony

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Function and Harmonic Purpose

Secondary dominants exist to create directed motion toward specific chords, making progressions feel more purposeful and dynamic than simple diatonic movement.

Creating Harmonic Pull

• Establishes a temporary tonic-dominant relationship with any diatonic chord, making that chord feel like a momentary "home"
• Intensifies the sense of arrival at the target chord through the leading tone's resolution, mimicking the strongest relationship in tonal music
• Enriches harmonic vocabulary by introducing chromatic notes while maintaining overall key coherence

Adding the Seventh

• Secondary dominant sevenths (V7/x) increase tension through the added dissonance of the minor seventh interval
• The seventh resolves downward by step to the third of the target chord, following standard dominant seventh voice leading
• Creates stronger forward momentum than simple triadic secondary dominants, making them especially common in jazz and Romantic-era music

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Resolution and Voice Leading

Proper resolution of secondary dominants reinforces the temporary tonicization and maintains the coherence of the overall progression.

Standard Resolution Patterns

• Secondary dominants resolve to their target chord—V/ii resolves to ii, V/vi resolves to vi, and so on
• The raised leading tone must resolve up by half-step to the root of the target chord, never left hanging or moving in the wrong direction
• Dominant sevenths resolve with the seventh moving down by step while the leading tone moves up, creating contrary motion

Voice Leading Principles

• Minimize large leaps between chord tones to maintain smooth, coherent lines
• Resolve tendency tones correctly—the chromatic leading tone goes up, the chordal seventh goes down
• Retain common tones where possible to create connections between harmonies and avoid choppy progressions

Common Progressions Using Secondary Dominants

• V/ii → ii → V → I creates a strong pre-dominant intensification, common in classical and pop music
• V/vi → vi provides a smooth deceptive-cadence alternative or a way to emphasize the relative minor
• Sequential patterns often chain secondary dominants (V/vi → vi → V/ii → ii → V → I), creating chromatic bass motion

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Tonicization vs. Modulation

Understanding the boundary between temporary emphasis and permanent key change is essential for accurate harmonic analysis.

Tonicization Characteristics

• Brief, temporary emphasis on a non-tonic chord lasting only one or two chords
• No establishment of new key area—the music returns to the original tonic without needing a pivot chord to get back
• Created specifically by secondary dominants that resolve and then yield to the home key's harmonic flow

Modulation Characteristics

• Extended presence in a new key with multiple cadences confirming the new tonic
• Requires a pivot chord or other transitional device to smoothly shift between key areas
• Creates a genuine sense of arrival in a new tonal center, not just a momentary detour

Analytical Distinctions

• Duration is key—if the "new tonic" lasts more than a few beats and receives cadential confirmation, consider it a modulation
• Check for return to original key—tonicizations snap back quickly; modulations require deliberate remodulation
• Context matters—a V/V in a four-bar phrase is tonicization; V/V followed by sixteen bars in the dominant key is modulation

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Style-Specific Applications

Different musical traditions employ secondary dominants in characteristic ways that reflect their harmonic languages.

Classical Usage

• Common in sequences and phrase extensions, creating directed harmonic motion toward structural goals
• Often prepared and resolved carefully with attention to voice leading and contrapuntal smoothness
• Supports formal structures like the move to V in sonata expositions or the circle-of-fifths progressions in Baroque music

Jazz and Popular Music

• Chromatic approach chords frequently use secondary dominants to create half-step bass motion
• Extended and altered dominants (V7♯9/ii, V7♭13/V) add color while maintaining secondary dominant function
• Tritone substitutions can replace secondary dominants, sharing the same tritone but with a different root

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Quick Reference Table

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Self-Check Questions

1. In C major, what chord would be labeled V7/vi, and what chromatic alteration does it contain compared to the diatonic chords in C major?

2. Compare and contrast tonicization and modulation: if you see V/V → V → I in a short phrase versus V/V → V → I → IV → V → I all in G major over sixteen bars, how would you analyze each differently?

3. Which two secondary dominants in a major key target minor chords, and what do they have in common in terms of their resolution tendencies?

4. A passage contains the progression V7/ii → ii → V7/V → V → I. Describe the voice leading for the chromatic alterations through this progression—which notes are raised, and where do they resolve?

5. How would you distinguish a V/IV chord from a I chord that's been reinterpreted as the tonic in a modulation to the subdominant key? What contextual clues would you look for in the surrounding music?